Systems and methods for using dynamic vascular assessment to improve vascular stent placement, application, design and marketing

ABSTRACT

The invention relates to systems and methods for assessing blood flow in single or multiple vessels and segments, for assessing vascular health, for conducting clinical trials, for screening therapeutic interventions for effect, for assessing risk factors, for evaluating intracranial pressure and for analyzing the results in a defined manner. The invention enables direct monitoring of therapies, substances and devices on blood vessels, especially those of the cerebral vasculature. Relevant blood flow parameters include mean flow velocity, systolic acceleration, and pulsatility index. Measurement and analysis of these parameters, and others, provides details regarding the vascular health of individual and multiple vessels and a global analysis of an individual&#39;s overall vascular health. The invention is applicable as both a system and method for monitoring and improving the design, performance, marketing and use of vascular stents. In particular, the invention enables DVA-assisted stenting procedures, including both pre-operative and post-operative management.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application claiming priorityto co-pending, commonly assigned U.S. patent application Ser. No.09/966,366 filed on Oct. 1, 2001 entitled “Decision Support Systems AndMethods For Assessing Vascular Health” and also claims priority to U.S.Provisional Applications No. 60/438,990, filed Jan. 1, 2003. The aboveapplications are expressly incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to systems and methods forassessing vascular health and for assessing the effects of treatments,risk factors and substances, including therapeutic substances, on bloodvessels, especially cerebral blood vessels, all achieved by measuringvarious parameters of blood flow in one or more vessels and analyzingthe results in a defined matter. In addition, the present inventionfurther pertains to collecting, analyzing, and using the measurement ofvarious parameters of blood flow in one or more vessels to establishprotocols for and to monitor clinical trials. Further, the presentinvention relates to an automated decision support system forinterpreting the values of various parameters of blood flow in one ormore vessels in assessing the vascular health of an individual.

2. Background Information

Proper functioning of the vascular system is essential for the healthand fitness of living organisms. The vascular system carries essentialnutrients and blood gases to all living tissues and removes wasteproducts for excretion. The vasculature is divided into differentregions depending on the organ systems served. If vessels feeding aspecific organ or group of organs are compromised, the organs andtissues supplied by those vessels are deleteriously affected and mayeven fail completely.

Vessels, especially various types of arteries, not only transmit fluidto various locations, but are also active in responding to pressurechanges during the cardiac cycle. With each contraction of the leftventricle of the heart during systole, blood is pumped through the aortaand then distributed throughout the body. Many arteries contain elasticmembranes in their walls which assist in expansion of the vessel duringsystole. These elastic membranes also function in smoothing pulsatileblood flow throughout the vascular system. The vessel walls of sucharteries often rebound following passage of the systolic pressurewaveform.

In auto-regulation, cerebral blood vessels maintain constant cerebralblood flow by either constricting or dilating over a certain meanarterial blood pressure range so that constant oxygen delivery ismaintained to the brain. Vascular failure occurs when the pressure dropstoo low and the velocity starts to fall. If the blood pressure gets toohigh and the vessels can no longer constrict to limit flow, thenbreakthrough, hyperemia breakthrough, and loss of auto-regulation occur.Both of these conditions are pathologic states, and have been describedin the literature in terms of mean arterial pressure and cerebral bloodflow velocity. But there are outliers that could not be explained basedon that model. The failure of the model is that it relies upon systemicblood pressure; the pressure of blood in the brain itself is not beingmeasured directly. The resultant pressure curve has an S-shaped curve.

The force applied to the blood from each heart beat is what drives itforward. In physics, force is equivalent to mass times acceleration. Butwhen blood is examined on a beat to beat variation, each heartbeatdelivers about the same mass of blood, unless there is severe loss ofblood or a very irregular heart rhythm. Therefore, as a firstapproximation, the force of flow on the blood at that particular momentis directly proportional to its acceleration.

Diseased blood vessels lose the ability to stretch. The elasticity orstretch of the blood vessel is very critical to maintaining pulsatileflow. When a muscle is stretched, it is not a passive relaxation. Thereis a chemical reaction that happens within the muscle itself that causesa micro-contracture to increase the constriction, so that when a bolusof blood comes through with each heartbeat, it stretches the bloodvessel wall, but the blood vessel then contracts back and gives the kickforward to maintain flow over such a large surface area with therelatively small organ of the heart. This generates a ripple of waves,starting in the large vessel of the aorta and working its way throughthe rest of the vessels. As vessels become diseased, they lose theability to maintain this type of pulsatile flow.

Further, if vessels are compromised due to various factors such asnarrowing or stenosis of the vessel lumen, blood flow becomes abnormal.If narrowing of a vessel is extensive, turbulent flow may occur at thestenosis resulting in damage to the vessel. In addition, blood may notflow adequately past the point of stenosis, thereby injuring tissuesdistal to the stenosis. While such vascular injuries may occur anywherethroughout the body, the coronary and cerebral vascular beds are ofsupreme importance for survival and well-being of the organism.Narrowing of the coronary vessels supplying the heart may decreasecardiovascular function and decrease blood flow to the myocardium,leading to a heart attack. Such episodes may result in significantreduction in cardiac function and death.

Abnormalities in the cerebral vessels may prevent adequate blood flow toneural tissue, resulting in transient ischemic attacks (TIAs), migrainesand stroke. The blood vessels which supply the brain are derived fromthe internal carotid arteries and the vertebral arteries. These vesselsand their branches anastomose through the great arterial circle, alsoknown as the Circle of Willis. From this circle arise the anterior,middle and posterior cerebral arteries. Other arteries such as theanterior communicating artery and the posterior communicating arteryprovide routes of collateral flow through the great arterial circle. Thevertebral arteries join to form the basilar artery, which itselfsupplies arterial branches to the cerebellum, brain stem and other brainregions. A blockage of blood flow within the anterior cerebral artery,the posterior cerebral artery, the middle cerebral artery, or any of theother arteries distal to the great arterior circle results incompromised blood flow to the neural tissue supplied by that artery.Since neural tissue cannot survive without normal, constant levels ofglucose and oxygen within the blood and provided to neurons by glialcells, blockage of blood flow in any of these vessels leads to death ofthe nervous tissue supplied by that vessel.

Strokes result from blockage of blood flow in cerebral vessels due toconstriction of the vessel resulting from an embolus or stenosis.Strokes may also arise from tearing of the vessel wall due to any numberof circumstances. Accordingly, a blockage may result in ischemic strokedepriving neural tissue distal to the blockage of oxygen and glucose. Atearing or rupture of the vessel may result in bleeding into the brain,also known as a hemorrhagic stroke. Intracranial bleeding exertsdeleterious effects on surrounding tissue due to increased intracranialpressure and direct exposure of neurons to blood.

Regardless of the cause, stroke is a major cause of illness and death.Stroke is the leading cause of death in women and kills more women thanbreast cancer. Currently, more than three quarters of a million peoplein the United States experience a stroke each year, and more than 25percent of these individuals die. Approximately one-third of individualssuffering their first stroke die within the following year. Furthermore,about one-third of all survivors of a first stroke experience additionalstrokes within the next three years.

In addition to its terminal aspect, stroke is a leading cause ofdisability in the adult population. Such disability can lead topermanent impairment and decreased function in any part of the body.Paralysis of various muscle groups innervated by neurons affected by thestroke can lead to confinement to a wheel chair, and muscular spasticityand rigidity. Strokes leave many patients with no ability to communicateeither orally or by written means. Often, stroke patients are unable tothink clearly and have difficulties naming objects, interacting withother individuals, and generally operating in society.

Strokes also result in massive expenditures of resources throughoutsociety, and place a tremendous economic burden on affected individualsand their families. It is estimated that the annual total costs in theUnited States economy alone is over $30 billion per year, with theaverage acute care stroke treatment costing approximately $35,000. Asthe population increases in age, the incidence of stroke will risedramatically. In fact, the risk of stroke doubles with ever succeedingdecade of life. Since the life expectancy of the population hasincreased dramatically during the last 100 years, the number ofindividuals over 50 years old has risen precipitously. In thispopulation of individuals living to ages never before expected, thepotential for stroke is very high indeed. Accordingly, the financial andemotional impact of cerebral vascular damage is expected to dramaticallyincrease during the next several decades.

Despite the tremendous risk of stroke, there are presently no convenientand accurate methods to access vascular health. Many methods rely oninvasive procedures, such as arteriograms, to determine whether vascularstenosis is occurring. These invasive techniques are often not ordereduntil the patient becomes symptomatic. For example, carotid arteriogramsmay be ordered following a physical examination pursuant to theappearance of a clinical symptom. Performing an arteriogram is notwithout risks due to introducing dye materials into the vascular systemthat may cause allergic responses. Arteriograms also use catheters thatcan damage the vascular wall and dislodge intraluminal plaque, which cancause an embolic stroke at a downstream site.

Many methods and devices available for imaging cerebral vessels do notprovide a dynamic assessment of vascular health. Instead, these imagingprocedures and equipment merely provide a snapshot or static image of avessel at a particular point in time. Cerebral angiography isconventionally held to be the “gold standard” of analyzing blood flow tothe brain. But this invasive method of analysis only provides the shapeof the vessels in an imaging modality. To obtain the same type of flowcriteria from an angiogram as one obtains from the present inventionwould entail extraordinary efforts and multiple dangerous procedures.

Instruments have been developed to obtain noninvasive measurements ofblood velocity in anterior arteries and veins using Doppler principles.In accordance with known Doppler phenomenon, these instruments providean observer in motion relative to a wave source a wave from the sourcethat has a frequency different from the frequency of the wave at thesource. If the source is moving toward the observer, a higher frequencywave is received by the observer. Conversely, if the wave source ismoving away from the observer, a lower frequency wave is received. Thedifference between the emitted and received frequencies is known as theDoppler shift. This Doppler technique may be accomplished through theuse of ultrasound energy.

The operation of such instruments in accordance with the Dopplerprinciple may be illustrated with respect to FIGS. 1 to 4. In FIG. 1,the ultrasound probe 40 acts as a stationary wave source, emittingpulsed ultrasound at a frequency of, e.g., 2 MHz. This ultrasound istransmitted through the skull 41 and brain parenchyma to a blood vessel42. For purposes of illustration, a blood cell 43 is shown moving towardthe probe and acts as a moving observer. As illustrated in FIG. 2, theblood cell reflects the pulse of ultrasound and can be considered amoving wave source. The probe receives this reflected ultrasound, actingas a stationary observer. The frequency of the ultrasound received bythe probe, f₁ is higher than the frequency, f₀, originally emitted. TheDoppler shift of the received wave can then be calculated. FIGS. 3 and 4show the effect on a pulse of ultrasound when blood flows in a directionaway from the probe. In this case, the received frequency, f₂, reflectedfrom the blood cell, is lower than the emitted frequency f₀. Again, theDoppler shift can be calculated.

The Doppler effect can be used to determine the velocity of blood flowin the cerebral arteries. For this purpose, the Doppler equation used isthe following:$F_{d} = \frac{2\quad F_{t}\quad V\quad\cos\quad\Theta}{V_{o}}$

-   -   where    -   F_(d)=Doppler frequency shift    -   F_(t)=Frequency of the transmitter    -   V=Velocity of blood flow    -   Φ=Angle of incidence between the probe and the artery    -   V₀=Velocity of ultrasound in body tissue

Typically, F_(t) is a constant, e.g., 2, 4 or 8 MHz, and V₀ isapproximately 1540 meters second (m/s) in soft body tissue. Assumingthat there is a zero angle of incidence between the probe and theartery, the value of cos Φ is equal to 1. The effect of the angle Φ isonly significant for angles of incidence exceeding 30°.

In exemplary instruments, ultrasonic energy is provided in bursts at apulse repetition rate or frequency. The probe receives the echoes fromeach burst and converts the sound energy to an electrical signal. Toobtain signal data corresponding to reflections occurring at a specificdepth (range) within the head, an electronic gate opens to receive thereflected signal at a selected time after the excitation pulse,corresponding to the expected time of arrival of an echo from a positionat the selected depth. The range resolution is generally limited by thebandwidth of the various components of the instrument and the length ofthe burst. The bandwidth can be reduced by filtering the receivedsignal, but at the cost of an increased length of sample volume.

Other body movements, for example, vessel wall contractions, can alsoscatter ultrasound, which will be detected as “noise” in the Dopplersignal. To reduce this noise interference, a high pass filter is used toreduce the low frequency, high amplitude signals. The high pass filtertypically can be adjusted to have a passband above a cutoff frequencyselectable between, e.g., about 0 and about 488 Hz.

Many health care providers rarely have such flow diagnostic capabilitiesat their disposal. For example, health care providers may be situated inremote locations such as in rural areas, on the ocean or in abattlefield situation. These health care providers need access toanalytical capabilities for analysis of flow data generated at theremote location. Health care providers facing these geographicimpediments are limited in their ability to provide the high qualitymedical services needed for their patients, especially on an emergencybasis. Further, both physicians and individuals concerned for their ownhealth are often limited in their ability to consult with specialists inspecific medical disciplines. Accordingly, a system that facilitatesaccess of physicians in various locations to sophisticated medicaldiagnostic and prognostic capabilities concerning vascular health isneeded. Such access would promote delivery of higher quality health careto individuals located throughout the country, especially in remoteareas removed from major medical centers.

There is also a need for a system whereby patient vascular data can betransmitted to a central receiving facility, which receives the data,analyzes it, produces a value indicative of the state of vascularhealth, and then transmit this information to another location, such asthe originating data transmitting station, or perhaps directly to thehealth care provider's office. This system should provide access tosophisticated computing capabilities that would enhance the accuracy ofhealth care providers' diagnostic and prognostic capabilities concerningvascular health. This system should be able to receive high volumes ofpatient data and rapidly process the data in order to obtain diagnosesand prognoses of disease. Such a system could be used for diagnosis andprognosis of any disease or condition related to vascular health.

There is a further need for a system that facilitates the ability of ahealth care provider to conveniently and rapidly transmit vascular flowdata parameters obtained from a patient to a location where consistent,reproducible analysis is performed. The results of the analysis can thenbe transmitted to the health care provider to facilitate accuratediagnosis or prognosis of a patient, to recommend treatment options, andto discuss the ramifications of those treatment options with thepatient.

There is also a need for a system that enables health care providers tomeasure the rate and type of developing vascular disease, and torecommend interventions that prevent, minimize, stabilize or reverse thedisease.

There is a further need for a system that enables health care providersto predict the vascular reaction to a proposed therapeutic intervention,and to modify the proposed therapeutic intervention if a deleterious oradverse vascular response is anticipated. Physicians often prescribetherapeutic substances for patients with conditions related to thecardiovascular system that may affect vascular health. For example,hypertensive patients may be prescribed beta-blockers with the intent oflowering blood pressure, thereby decreasing the probability of a heartattack. Patients frequently receive more than one therapeutic substancefor their condition or conditions. The potential interaction oftherapeutic substances at a variety of biological targets, such as bloodvessels, is often poorly understood. Therefore, a non-invasive methodthat can be used to assess the vascular effects of a substance, such asa therapeutic substance, or a combination of therapeutic substances isneeded. A clear understanding of the vascular effects of one or moresubstances on blood vessels may prevent prescriptions of substances withundesirable and potentially lethal effects, such as stroke, vasospasmand heart attack. Accordingly, what is needed is a system and methodthat can be used for repeated assessment without deleterious effects ofpotential vascular effects of a substance, or combination of substances,in a patient population during a clinical trial. Such clinical studiesmay also reveal dosages of individual substances and combinations ofsubstances at specific dosages that provide desirable and unexpectedeffects on blood vessels.

Furthermore, a system and method that can provide an assessment of thevascular health of an individual is needed. Also needed is a system andmethod that may be used routinely to assess vascular health, such asduring periodic physical examinations. This system and method preferablyis non-invasive and provides information concerning the compliance andelasticity of a vessel. Also needed is a system and method that may beused to rapidly assess the vascular health of an individual. Suchsystems and methods should be available for use in routine physicalexaminations, and especially in the emergency room, intensive care unitor in neurological clinic. What is also needed is a system and methodwhich can be applied in a longitudinal manner for each individual sothat the vascular health of the individual may be assessed over time. Inthis manner, a problem or a disease process may be detected before theappearance of a major cerebral vascular accident or stroke.

In addition, there is a need for a system and method for assessingwhether treatments, risk factors and substances affect blood vessels,particularly cerebral blood vessels, so that their potential for causingvascular responses may be determined. By determining the vasculareffects of treatments, risk factors and substances, physicians mayrecommend that a patient avoid the treatment, risk factor and/orsubstance. Alternatively, desirable vascular effects of a treatment,therapeutic intervention and/or substance may result in administrationof the treatment, therapeutic intervention and/or substance to obtain adesired effect.

In addition, there is also needed a system and method for assessing theefficacy of a treatment, including conducting a procedure, carrying outa therapy, and administering a pharmaceutical substance, in treatingvascular disorders, so that identification of those treatments mostefficacious in the treatment of vascular disorders can be determined andemployed to restore vascular health.

As required by federal regulations, treatments, including drugs andother therapies intended for treating individuals, have to be tested inpeople. These tests, called clinical trials, provide a variety ofinformation regarding the efficacy of treatment, such as whether it issafe and effective, at what doses it works best, and what side effectsit causes. This information guides health professionals and, fornonprescription drugs, consumers in the proper use of medicines. Incontrolled clinical trials, results observed in patients beingadministered a treatment are compared to results from similar patientsreceiving a different treatment such as a placebo or no treatment atall. Controlled clinical trials are the only legal basis for the UnitedStates Food and Drug Administration (“FDA”) in determining that a newtreatment provides “substantial evidence of effectiveness, as well asconfirmation of relative safety in terms of the risk-to-benefit ratiofor the disease that is to be treated.”

It is important to test drugs, therapies, and procedures in thoseindividuals that the treatments are intended to help. It is alsoimportant to design clinical studies that ask and answer the rightquestions about investigational treatment. Before clinical testing isinitiated, researchers analyze a treatment's main physical and chemicalproperties in the laboratory and study its pharmacological and toxiceffects on laboratory animals. If the results from the laboratoryresearch and animal studies show promise, the treatment sponsor canapply to the FDA to begin testing in people. Once the FDA has reviewedthe sponsor's plans and a local institutional review board—typically apanel of scientists, ethicists, and nonscientists that oversees clinicalresearch at medical centers—approves the protocol for clinical trials,clinical investigators give the treatment to a small number of healthyvolunteers or patients. These Phase 1 studies assess the most commonacute adverse effects and examine the size of doses that patients cantake safely without a high incidence of side effects. Initial clinicalstudies also begin to clarify what happens to a drug in the human body,e.g., whether it's changed, how much of it is absorbed into thebloodstream and various organs, how long it is retained within the body,how the body rids the drug, and the effect(s) of the drug on the body.

If Phase 1 studies do not reveal serious problems, such as unacceptabletoxicity, a clinical study is then conducted wherein the treatment isgiven to patients who have the condition that the treatment is intendedto treat. Researchers then assess whether the treatment has a favorableeffect on the condition. The process for the clinical study simplyrequires recruiting one or more groups of patients to participate in aclinical trial, administering the treatment to those who agree toparticipate, and determining whether the treatment helps them.

Treatments usually do not miraculously reverse fatal illnesses. Moreoften, they reduce the risk of death but do not entirely eliminate it.This is typically accomplished by relieving one or more symptoms of theillness, such as nasal stuffiness, pain, or anxiety. A treatment mayalso alter a clinical measurement in a way that physicians consider tobe valuable, for example, reduce blood pressure or lower cholesterol.Such treatment effects can be difficult to detect and evaluate. This ismainly because diseases do not follow a predictable path. For example,many acute illnesses or conditions, such as viral ailments likeinfluenza, minor injuries, and insomnia, go away spontaneously withouttreatment. Some chronic conditions like arthritis, multiple sclerosis,or asthma often follow a varying course, e.g., better for a time, thenworse, then better again, usually for no apparent reason. Heart attacksand strokes have widely variable death rates depending on treatment,age, and other risk factors, making the “expected” mortality for anindividual patient hard to predict.

A further difficulty in gauging the effectiveness of an investigationaltreatment is that in some cases, measurements of disease are subjective,relying on interpretation by the physician or patient. In thosecircumstances, it's difficult to tell whether treatment is having afavorable effect, no effect, or even an adverse effect. The way toanswer critical questions about an investigational treatment is tosubject it to a controlled clinical trial.

In a controlled trial, patients in one group receive the investigationaltreatment. Those in a comparable group, the control group, receiveseither no treatment at all, a placebo (an inactive substance that lookslike the investigational drug), or a treatment known to be effective.The test and control groups are typically studied at the same time.Usually, the same group of patients is divided into two sub-groups, witheach subgroup receiving a different treatment.

In some special cases, a study uses a “historical control,” in whichpatients given the investigational treatment are compared with similarpatients treated with the control treatment at a different time andplace. Often, patients are examined for a period of time after treatmentwith an investigational treatment, with the investigators comparing thepatients' status both before and after treatment. Here, too, thecomparison is historical and based on an estimate of what would havehappened without treatment. The historical control design isparticularly useful when the disease being treated has high andpredictable death or illness rates. It is important that treatment andcontrol groups be as similar as possible in characteristics that canaffect treatment outcomes. For example, all patients in a specific groupmust have the disease the treatment is meant to treat or the same stageof the disease. Treatment and control groups should also be of similarage, weight, and general health status, and similar in othercharacteristics that could affect the outcome of the study, such asother treatment(s) being received at the same time.

A principal technique used in controlled trials is called“randomization.” Patients are randomly assigned to either the treatmentor control group rather than deliberately selected for one group or theother. An important assumption, albeit a seriously flawed one, is thatwhen the study population is large enough and the criteria forparticipation are carefully defined, randomization yields treatment andcontrol groups that are similar in important characteristics. Becauseassignment to one group or another is not under the control of theinvestigator, randomization also eliminates the possibility of“selection bias,” the tendency to pick healthier patients to get the newtreatment or a placebo. In a double-blind study, neither the patients,the investigators, nor the data analysts know which patients got theinvestigational drug.

Unfortunately, careful definition of selection criteria for matchingparticipation in clinical trials has not been conventionally available.Vascular health, and more particularly cerebrovascular health, has beena criterion that has been difficult, if not impossible, to assess forpossible clinical trial participants. Thus, there remains a need in theart for the ability to truly randomize clinical trials by choosing trialparticipants with matched vascular and cerebrovascular characteristics.

Moreover, an important aspect of clinical trials is to assess the riskof adverse effects of a given treatment. This can be difficult foradverse effects that manifest themselves only long after the short runof a clinical trial has run its course. Unfortunately, vascular effects,and more particularly cerebrovascular adverse effects, are difficult, ifnot impossible, to assess during the course of a clinical trial. Thus,there remains a need in the art for the ability to accurately assessadverse effects brought about by a treatment upon vascular andcerebrovascular health characteristics.

There is also needed a system and method for assessing the efficacy of atreatment, including conducting a procedure, carrying out a therapy, andadministering a pharmaceutical substance or combinations thereof intreating vascular disorders, so that identification of deleterioustreatments can be determined and no longer be prescribed.

Further, there is a need for a system and method for assessing theimpact of a treatment, including conducting a procedure, carrying out atherapy, and administering a pharmaceutical substance, or combinationsof pharmaceutical substances, upon vascular health, so that the impactof a treatment which have an effect upon vascular health can beascertained.

SUMMARY OF THE INVENTION

The present invention provides a solution to the above-describedshortcomings by providing a system and method for assessing the vascularhealth of an individual. This system and method is inexpensive, rapid,non-invasive, and provides superior data concerning the dynamic functionof the vasculature. Accordingly, this system and method may be used in awide variety of situations including, but not limited to, periodicphysical examinations, in an intensive care unit, in an emergency room,in the field such as in battlefield situations or at the scene of anemergency on the highway or in the country, and in a neurologicalclinic. The use of this system and method enables physicians to evaluateindividuals not only for their current state of vascular health, butalso to detect any deviations from vascular health by evaluatingspecific parameters of vascular function.

In addition to use during routine physical examinations, the presentsystem and method may be used to evaluate individuals with the riskfactors for cerebral vascular malfunction. Such risk factors include,but are not limited to a prior history of stroke, a geneticpredisposition to stroke, smoking, alcohol consumption, caffeineconsumption, obesity, hypertension, aneurysms, arteritis, transientischemic episodes (TIAs), closed head injury, history of migraineheadaches, prior intracranial trauma, increased intracranial pressure,and history of drug abuse.

In addition to providing a system and method for evaluating individualswith high risk factors, the present system and method also provides amechanism for selecting patient groups for clinical trials andmonitoring patient populations in specific clinical groups. For example,a patient population of individuals at high risk of stroke may beevaluated systematically over time to determine whether ongoing vascularchanges may indicate an incipient cerebral vascular event, such asstroke. In this manner, it may be possible to predict the occurrence ofa first stroke, thereby preventing the stroke. In another embodiment,the present invention provides a mechanism for monitoring individualswho have experienced a stroke.

In yet a further embodiment of the present invention, the vascularreactivity of an individual to various substances, including but notlimited to drugs, nutrients, alcohol, nicotine, caffeine, hormones,cytokines and other substances, may be evaluated. Through the use ofthis system and method, research studies may be conducted using animalsor humans to evaluate the effects of various substances on the vascularsystem. By performing the noninvasive, low cost and efficient tests ofthe present invention, valuable information concerning the potentialvascular effects of a substance may be collected and assessed before thesubstance is medically prescribed. Furthermore, vascular effects ofdosages of individual substances and combinations of substances atdifferent dosages may be evaluated in selected clinical populationsusing the system and method of the present invention. Accordingly, thepresent invention provides a system and method for performingnon-invasive clinical research studies to evaluate potential vasculareffects of substances, or combinations of substances, at selecteddosages and in selected patient populations.

In another embodiment, the present invention may be applied to specificpopulations of individuals who have had specific illnesses to determinewhether application of a substance may produce undesirable effects inthat population. For example, a population of diabetic individuals mayreact differently to a specific substance such as a drug than anon-diabetic population. Further, a population of hypertensiveindividuals may react differently to a specific substance, such as acatecholaminergic agonist drug or an ephedrine-containing naturalextract, than a non-hypertensive population. The use of the presentinvention permits an assessment of vascular reactivity in any individualor any population, whether it be a population of individuals withspecific diseases, conditions or prior exposures to various therapies.

By means of the present invention, a method of assessing vascular healthin a human or an animal is provided. In one embodiment, this assessmentmethod comprises the steps of obtaining information concerning flowvelocity within a vessel; calculating a mean flow velocity value for thevessel; calculating a systolic acceleration value for the vessel; andinserting the mean flow velocity value and the systolic accelerationvalue into a schema for further analysis of the calculated values. Suchschema can consist of multiple arrangements of such values, includingbut not limited to diagrams, graphs, nomograms, spreadsheets anddatabases, thereby permitting operations such as mathematicalcalculations, comparisons and ordering to be performed that include thecalculated values.

In one embodiment, the assessment method may further comprisecalculating a pulsatility index. With the pulsatility index calculated,the assessment method of is able to plot the pulsatility index, thesystolic acceleration value, and the mean flow velocity value for thevessel in a 3-dimensional space, wherein the plot of the pulsatilityindex, the systolic acceleration value, and the mean flow velocity valuein 3-dimensional space produce a first characteristic value for thevessel. This first characteristic value for the vessel may then becompared to other first characteristic values obtained from measurementsof flow velocity collected from similar vessels from other humans oranimals to determine whether the vessel is in an auto-regulation mode.

The assessment method may further comprise collecting informationconcerning an additional variable, transforming the information into avalue, and plotting the value in n-dimensional space together with thepulsatility index, the systolic acceleration value, and the mean flowvelocity value to produce a second characteristic value for the vessel.The second characteristic value can then be compared to secondcharacteristic values obtained from measurements of flow velocitiescollected from similar vessels from other humans or animals to determinewhether the vessel is in an auto-regulation mode.

The vessel of the assessment method as described above can be anintracranical vessel. Further, the vessel can be an artery. The arterycan be one that supplies the central nervous system. Further, the arterycan be selected from the group consisting of the common carotid,internal carotid, external carotid, middle cerebral, anterior cerebral,posterior cerebral, anterior communicating, posterior communicating,vertebral, basilar, ophthalmic, and branches thereof.

The information collected in the assessment method described aboveconcerning flow velocity can be gathered using ultrasound energy. Thisgathering of flow velocity information can further be gathered by use ofa Doppler probe.

The effects of a substance on a vessel can be determined by applying theassessment method as described above both before and after administeringthe substance. This substance can be a drug. The drug may be avasoactive drug. The substance may be suspected of having vascularactivity.

The assessment method described above may be utilized in the instancewherein the human or the animal is suspected of having or has a vasculardisease or a condition that affects vascular function. The human or theanimal can be analyzed at a time of normal and at a time of abnormalhealth.

The present invention further provides for a method of assessingvascular effects of a treatment in a human or an animal. This methodincludes the steps of collecting a first set of information concerningflow velocity within a vessel; administering the drug; collecting asecond set of information concerning flow velocity within the vessel;calculating a mean flow velocity value for the vessel; calculating asystolic acceleration value for the vessel; and inserting the mean flowvelocity value and the systolic acceleration value into a schema foranalysis of the calculated values.

The step of administering a treatment in the vascular effects assessmentmethod can be selected from the group consisting of administering adrug, conducting a procedure, and carrying out a therapy. When theadministration comprises administering a drug, the drug may include astatin. The statin administered can include Atorvastatin calcium.

The steps of collecting the first set of information and collecting thesecond set of information in the vascular assessment method describedabove can be performed using ultrasound energy. More specifically, thecollection steps can be performed using a Doppler probe.

The present invention further provides for a method of assessingvascular effects of a treatment in a human or an animal. The treatmentcan include conducting a procedure, carrying out a therapy, andadministering a drug. This method includes the steps of collecting afirst set of information concerning flow velocity within a vessel;obtaining a first mean flow velocity value before administration of thetreatment; obtaining a first systolic acceleration value beforeadministration of the treatment; administering the treatment; collectinga second set of information concerning flow velocity within the vessel;obtaining a second mean flow velocity value following administration ofthe treatment; obtaining a second systolic acceleration value afteradministration of the treatment; comparing the first mean flow velocityvalue and the second mean flow velocity value; and comparing the firstsystolic acceleration value and the second systolic acceleration valueto determine if the treatment had a vascular effect.

The method of assessing the vascular effects of a treatment as describedabove may further include the steps of calculating a first pulsatilityindex from the first set of information; calculating a secondpulsatility index from the second set of information; plotting the firstpulsatility index, the first mean flow velocity value, and the firstsystolic acceleration value to produce a first characteristic value forthe vessel; plotting the second pulsatility index, the second mean flowvelocity value and the second systolic acceleration value to produce asecond characteristic value for the vessel; and comparing the firstcharacteristic value and the second characteristic value to determine ifthe drug had a vascular effect.

The step of administering a treatment in the method of assessingvascular effects of a treatment as described above can be selected fromthe group consisting of administering a drug, conducting a procedure,and carrying out a therapy. When the administration includesadministering a drug, the drug can include a statin. When a statin isadministered, the statin can include Atorvastatin calcium.

The steps of collecting the first set of information and collecting thesecond set of information in the method of assessing vascular effects ofa treatment as described above can be performed using ultrasound energy.More specifically, the collection can be performed by means of a Dopplerprobe.

The method of assessing vascular effects of a treatment as describedabove may be used when the human or the animal has a risk factor for astroke. The human or the animal may have received at least onemedication before collecting the first set of information.

The method of assessing vascular effects of a treatment as describedabove may be used to determine if the drug may cause undesirablevascular effects in the human or the animal receiving the medication.

The method of assessing vascular effects of a drug as described abovecan be used when the human or the animal has a vascular disease or acondition that affects vascular function.

In another embodiment of the present invention, a method of assessingvascular effects of a treatment in humans or animals is provided. Themethod of accessing the vascular effects includes assigning individualhumans or animals to different groups for each human or animal byperforming the steps of obtaining a first set of information concerningflow velocity within a vessel; obtaining a first mean flow velocityvalue before administration of the drug; obtaining a first systolicacceleration value before administration of the treatment; administeringthe treatment; obtaining a second set of information concerning flowvelocity within the vessel; obtaining a second mean flow velocity valuefollowing administration of the treatment; obtaining a second systolicacceleration value after administration of the treatment; comparing thefirst mean flow velocity value and the second mean flow velocity value;comparing the first systolic acceleration value and the second systolicacceleration value to determine if the treatment had a vascular effect;and statistically analyzing data for each individual before and afteradministration of the treatment.

The administration of the treatment in the method of assessing vasculareffects of a treatment by assigning individual humans or animals todifferent groups as described above can be selected from the groupconsisting of administering a drug, conducting a procedure, and carryingout a therapy. When the administration of a drug is selected, the drugmay include a statin. The statin can be Atorvastatin calcium.

The data collection step in the method of assessing vascular effects ofa treatment by assigning individual humans or animals to differentgroups as described above can be performed using ultrasound energy.Further, the data collection step can be performed using a Dopplerprobe.

The method of assessing vascular effects of a treatment by assigningindividual humans or animals to different groups as described above canfurther include statistically analyzing data within each group beforeand after administration of the treatment.

In one embodiment, the present invention further provides for a methodof screening for adverse effects of a treatment. The screening methodincludes the steps of applying the treatment to a number of individuals;monitoring the cerebrovascular blood flow of such individuals afterapplying the treatment; and identifying adverse effects tocerebrovascular blood flow in such individuals arising after applyingthe treatment.

The data regarding cerebrovascular health status obtained by thescreening method of the present invention can include both the mean flowvelocity value for intracranial blood vessels of the individuals andsystolic acceleration value for intracranial blood vessels of theindividuals. The intracranial vessels can be arteries. The arteries canbe selected from the group consisting of is the common carotid, internalcarotid, external carotid, middle cerebral, anterior cerebral, posteriorcerebral, anterior communicating, posterior communicating, vertebral,basilar, and branches thereof. The data obtained may also include apulsatility index.

The screening method permits quantitative data regarding thecerebrovascular blood flow of a number of individuals to be obtained.The quantitative data obtained may be collected by the use of ultrasoundenergy. Further, a Doppler probe can be used to collect the dataregarding cerebrovascular health status.

The screening method treatment applied can include at least onetreatment selected from the group consisting of administering a drug,conducting a procedure, and carrying out a therapy.

When the treatment selected is administration of a drug, the drug orsubstance can be a vasoactive drug, or a drug suspected of havingvascular activity

The screening method for adverse effects of a treatment on a vessel asdescribed above may be applied both before and after administration ofthe treatment.

The screening method for adverse effects of a treatment on a vessel asdescribed above may be applied on individuals suspected of having oractually having a vascular disease or a condition that affects vascularfunction.

The present invention comprises measurements of parameters of vascularfunction. Specifically, the present invention uses energy including, butnot limited to, sound energy and any form of electromagnetic energy, todetermine the rate of movement of cells through vessels. While notwanting to be bound by the following statement, it is believed that redblood cells account for the majority of cells detected with thistechnique. In a preferred embodiment, ultrasound energy is utilized.

According to the present invention, a sample volume of red blood cellsis measured utilizing sound energy. Because not all blood cells in thesample volume are moving at the same speed, a range or spectrum ofDoppler shifted frequencies are reflected back to the probe. Thus, thesignal from the probe may be converted to digital form by ananalog-to-digital converter, with the spectral content of the sampledDoppler signal then calculated by computer or digital signal processorusing a fast Fourier transform method. This processing method produces avelocity profile of the blood flow, which varies over the period of aheartbeat. The process is repeated to produce a beat-to-beat flowpattern, or sonogram, on a video display. The instrument can beconfigured to analyze multiple separate frequency ranges within thespectrum of Doppler signals. Color coding may be used to show theintensity of the signal at different points on the spectral line. Theintensity of the signal represents the proportion of blood cells flowingwithin that particular velocity range. The information displayed on thevideo screen can be used by a trained observer to determine blood flowcharacteristics at particular positions within the brain of theindividual being tested, and can be used to detect anomalies in thatblood flow such as the presence of a blockage or restriction, or thepassage of an embolus through the artery, which introduces a transientdistortion of the displayed information. The instrument can also includea processing option that provides a maximum frequency follower orenvelope curve displayed on the video screen as the white outline of theflow spectrum.

In another preferred embodiment, coherent light in the form of lasersmay be employed. In yet another embodiment, infrared or ultravioletradiation may be employed.

In one preferred embodiment, the system and method of the presentinvention permits a determination of vascular health based on ananalysis of two blood flow parameters, mean flow velocity and systolicacceleration.

Earlier studies have analyzed how blood velocity correlates with bloodflow to the brain. Flow is a concept different from velocity; flow isthe quantity per unit time delivered to a certain region of the brain.This is partially dependent on velocity. Accordingly, the earlierstudies demonstrate a one-to-one relationship between flow and velocity.Therefore, mean flow velocity is a very good indicator of cerebral bloodflow. Thus, conventionally, this theory has been relied upon todetermine blood flow to the brain. There is a second calculated numbercalled the pulsatility index, which is the resistance of blood flowdownstream, which others have also measured. Still, there is a need toexamine any combination of flow parameters to assess vascular health orauto-regulation.

In a more preferred embodiment of the present invention, transcranialDoppler is used to obtain the velocity measurements described above.Application of a selected form of energy to cells within the vesselspermits a calculation of the flow rate of the cells within the vessels.By measuring specific parameters involved in the flow of cells throughvessels, a data analysis may be performed.

One parameter of relevance to the present invention is mean blood flowvelocity (V_(m)). The value of this parameter is given by the equation$V_{m} = {\frac{V_{s} - V_{d}}{3} + V_{d}}$

-   -   where    -   V_(s)=peak systolic velocity, and    -   V_(d)=end diastolic velocity.

A second parameter of relevance to the present invention is thepulsatility index (P_(i)). The value of this parameter is given by theequation $P_{i} = \frac{V_{s} - V_{d}}{V_{m}}$

-   -   where    -   V_(m)=mean blood flow velocity    -   V_(s)=peak systolic velocity, and    -   V_(d)=end diastolic velocity.

Another parameter of relevance to the present invention is systolicacceleration. This variable is determined by measuring the flow velocityat the end of diastole, measuring the flow velocity at peak systole, andthen dividing the difference between these measures by the length oftime between the end of diastole and the time of peak systolic velocity.This is an index of systolic acceleration. The value of this parameteris given by the equation— $A = \frac{V_{s} - V_{d}}{t_{s} - t_{d}}$

-   -   where    -   t_(s)=time at V_(s) and t_(d)=time at V_(d)    -   V_(s)=peak systolic velocity, and    -   V_(d)=end diastolic velocity.

In one preferred embodiment of the present invention, a characteristicsignature for each vessel is defined by plotting the systolicacceleration against the mean flow velocity. With mean flow velocityplotted on the y-axis and systolic acceleration plotted on the x-axis, avessel may be represented as a point on this graph.

The present invention reveals that vessels are in a state of normalauto-regulation when their vascular state values fall within theauto-regulating regions of the above described graph. A point on thegraph represents a vascular state of a vessel. It has also beendetermined that when the value for an individual vessel falls withinother regions of the graph outside the zone of auto-regulation, seriousproblems have either occurred or may be ongoing. Accordingly, thepresent invention permits not only a determination of the location ofeach individual vessel on such a graph, but also provides insight intothe vascular health of a vessel in view of its deviation in distanceand/or direction from what may be considered within the normal range ofsuch vessels.

In another preferred embodiment of the present invention, anothercharacteristic signature for each vessel is defined by plotting thesystolic acceleration relative to the mean flow velocity and thepulsatility index. With mean flow velocity plotted on the y-axis,pulsatility index plotted on the z-axis, and systolic accelerationplotted on the x-axis, a vessel may be represented as a point in this3-dimensional space.

The present invention further reveals that vessels are in a state ofnormal auto-regulation when their values fall in certain regions of this3-dimensional space. The 3-dimensional plot provides a characteristicshape representing a cluster of points, wherein each point representsthe centroid from an individual's specific vessel. It has further beendetermined that when the value for an individual vessel falls in otherregions of the 3-dimensional space outside the zone of auto-regulation,serious problems have either occurred or may be ongoing. Accordingly,the present invention permits not only a determination of the locationof each individual vessel on such a graph, but also provides insightinto the vascular health of a vessel in view of its deviation, either indistance and/or direction, from what may be considered within the normalrange of such vessels.

By means of the present invention, it has been determined that eachcerebral vessel has a characteristic state and signature represented ina 3-dimensional graph. The characteristic state and signature for onevessel of an individual can be represented as a point in the vascularstate diagram, and the characteristic states and signatures for apopulation of the same vessel type can be represented by a set of pointsdescribed as a mathematical centroid. This value for the centroid isobtained through those analyses described above. The present inventionreveals that individual vessels, especially individual cerebral vessels,display a clustering of points in 3-dimensional space that defines ashape.

It is to be understood that other variables may be employed in additionto systolic acceleration, mean flow velocity, and pulsatility index toprovide additional information concerning specific vessels. Whenadditional variables are employed, the data may then be plotted in a4-dimensional or more dimensional space. Analysis of a specific centroidvalue for a vessel from an individual, in terms of its distance from themean value for centroids for the same named vessel taken from otherindividuals, provides a basis for assessing the significance ofdifferences between normal and abnormal vessels and enables predictionsof abnormality. Accordingly, the present invention is not limited to3-dimensional space. Further, individual vessels may be represented inn-dimensional space, wherein each dimension may be a relevant clinicalparameter. For example, additional dimensions or variables may include,but are not limited to, age, clinical history or prior stroke, riskfactors such as obesity, smoking, alcohol consumption, caffeineconsumption, hypertension, closed head injury, history of migraineheadaches, vasculitis, TIAs, prior intracranial trauma, increasedintracranial pressure, history of drug abuse, steroid administrationincluding estrogen and/or progesterone, lipid deposition,hyperlipidemia, parathyroid disease, abnormal electrolyte levels,adrenal cortical disease, atherosclerosis, arteriosclerosis,calcification, diabetes, renal disease, prior administration oftherapeutic agents with vascular effects, prior administration oftherapeutic agents with effects on the release or reuptake ofnorepinephine at postganglionic sympathetic nerve endings, prioradministration of therapeutic agents with effects on the release orreuptake of acetylcholine at postganglionic parasympathetic nerveendings, vascular denervation, shock, electrolyte levels, pH, pO₂, pCO₂,or any combination thereof.

The present invention permits analysis of all the vessels of anindividual. These analytical methods provide an index of the vascularhealth of the individuals, especially the compliance of individualvessels. In a preferred embodiment, the present invention permitsanalysis of a vessel's ability to auto-regulate. Any such vessel may beanalyzed provided it can be located with the device used to analyzeblood flow. Both arteries and veins may be analyzed with the system andmethod of the present invention. Regarding arteries, both cerebral andnon-cerebral vessels may be analyzed. For example, the common carotid,internal carotid artery, external carotid artery and other extracranialarteries may be evaluated. Further, analysis of the cerebral vessels ofan individual can be performed with the system and method of the presentinvention, including the vessels contributing to the great arterialcircle and their primary branches. The present invention further permitsanalysis of individual cerebral vessels from individuals in differentgroups, for example, groups within specific age ranges or at specificages, groups considered healthy, groups which may fall into a clinicallydefined group, such as diabetics, groups of individuals who share commonrisk factors such as obesity, groups of individuals exposed to similarsubstances, such as nicotine, or pharmaceuticals, such as beta blockers.

The present invention includes a system having the capability for avariety of communication mechanisms such as access to the Internet thatprovides accurate prediction of the future occurrence of vasculardisease, vascular disease diagnosis, determination of the severity ofvascular disease, and/or vascular disease prognosis. The presentinvention provides one or more highly sophisticated computer-baseddatabases trained to diagnose, prognose, determine the severity of andpredict the future occurrence of vascular disease, and provide increasedaccuracy of diagnosis and prognosis.

The system of the present invention can operate by receiving patientvascular data from another location through a receiver or data receivingmeans, transmitting the data into a computer or through severalcomputers containing vascular data for that specific vessel or numerousvessels in normal and/or diseased states, comparing the patient'svascular data to the database to produce one or more results, andtransmitting the one or more results to another location. The otherlocation may be a computer in a remote location, or other data receivingmeans.

In one embodiment of an automated decision support system forinterpreting the values of various parameters of blood flow in one ormore vessels in assessing the vascular health of an individual accordingto the present invention, at least three different modules arepresented, each interactive with the other. These modules include amodule for accessing data, a module for interfacing with a user, andmodule for processing patient data, or reasoning module.

The data access module provides access and storage methods fortranscranial Doppler and clinical data inputted by a user, and forinferences from the reasoning engine. This data may be stored by anymethod known to those skilled in the art, including but not limited tostorage on a network server, or storage in a file on a personalcomputer. The data access module is able to respond to a variety ofcommands, including but not limited to a command to initialize themodule, one to retrieve patient data, a command to save patient dataand/or graphs, a command to delete patient data and/or graphs, a commandto retrieve a list of patients, and a command to query the database.

The user interface module performs various functions, including but notlimited to processing user input to be sent to the data access module,running commands for the reasoning module, querying about patient datafor the data access module, and querying about inference results fromthe reasoning module. The user interface module may further be designedto display patient data for at least one patient received from the dataaccess module and concept instances received from the reasoning module.The user interface module can also be designed to display clinical anddemographic data for a patient, raw transcranial Doppler velocimetrydata, and an analysis of a patient's hemodynamic state. The analysis ofthe patient's hemodynamic state includes, but is not limited to thecondition of each artery, any global conditions detected, and anassessment of the patient's risk for stroke. The user interfacepreferably provides a user the ability to drill down from a patient'sassessment of the risk for stroke in order to determine how conclusionswere reached.

The reasoning interface module performs various functions, including butnot limited to accepting commands to process patient data for inferredconcepts, searching for instances of particular concepts or evidence ofa given concept instance in a concept graph, and saving the conceptgraph or loading an old concept graph. The reasoning interface can befurther broken down into at least two other modules—an analysis modulefor performing analysis of the data inputted, including but not limitedto any user input, saved concepts and/or data, clinical data, andtranscranial Doppler data; and an interface module for hiding thedetails of the interaction of the analysis module with the othermodules. The interface module allows other modules to access data andconcept graphs residing in the analysis module without exposure to theanalysis interface. Preferably, those files created by the reasoningmodule are stored by the data access module.

According to the present invention, patient data includes all dataderived from transcranial Doppler readings and all clinical data.Preferably, patient data is accessed and stored as a single block ofdata for each patient, referenced by a unique patient ID.

In one embodiment of the present invention, transcranial Doppler dataand clinical data is inputted by a user at the user interface. Once theinput has been completed, the user can either save the data to a filefor later access, or can immediately analyze the data before saving it.In either instance, patient data is retrieved by the reasoning modulefrom the data access module. Both modules retrieve patient data based onpatient ID. Preferably, a user is able to retrieve a list of allpatients saved in a file in order to be able to select a particularpatient's data to view, edit, or analyze. Preferably, although notnecessary, the set of parameters sent to the data access module includesa user ID.

The analysis module is able to provide one or more classes of service.For example, the module includes methods for commanding the analysismodule, including commands for initializing, starting, running andstopping the module. Another class of service provided by the module mayinclude methods for setting and/or retrieving concept attribute values.

As defined by the above described modules, the present invention is ableto provide the sequences for an automated decision support system forinterpreting the values of various parameters of blood flow in one ormore vessels in assessing the vascular health of an individual. Thesesequences include but are not limited to saving patient data, analyzingpatient data, loading an analysis to an analysis page, and retrievingevidence from a concept graph.

By means of the above described modules, the present invention is ableto provide the software design for an automated decision support systemfor interpreting the values of various parameters of blood flow in oneor more vessels in assessing the vascular health of an individual.

With the use of the above described modules, the present invention isable to provide the use cases for an operational prototype for anautomated decision support system for interpreting the values of variousparameters of blood flow in one or more vessels in assessing thevascular health of an individual. These use cases, or user interfacecommands, include but are not limited to entering new patient data,loading existing patient data, viewing clinical data, viewingtranscranial Doppler velocimetry, analyzing patient data, viewinganalyses, and gathering the evidence behind an analysis.

In a preferred embodiment of the present invention, there is provided aprocess by which the vascular health assessment can be carried outremotely, allowing for interrogation of a patient's vascular health atone location, while processing the patient's data information obtainedby ultrasound measurements of the cerebral vascular health state fromvarious flow parameters is done at another location. This process ispreferably managed in a stepwise fashion using a decision matrixdeveloped to obtain the appropriate data set given the patient'sparticular situation at the time. Therefore, the process can be remotelymanaged and the data can be remotely processed.

For example, a technician or physician would assist a patient byapplying to the patient's head an appropriate device that would obtainthe necessary transcranial Doppler data, or alternatively, a probe wouldbe placed at appropriate windows on the skull to obtain the Dopplerdata. The vascular health data would then be collected and transmittedto another device that would perform the vascular health assessment. Thedata would then be processed and an interpretation generated, as well aspotential recommendations for additional measurements. The assessmentprocess itself could be done one test at a time in batch mode, or itcould be done continuously on an online system. The interpretation andpotential recommendations can then be relayed to another location, thislocation can be any of several choices, including the location of thepatient, the location of the health care provider, or the location wherethe diagnosis will be communicated.

In executing the analysis, the analyst, e.g., a computer or assessor,would perform the analysis and, preferably, do a comparison to areference population. The reference population could be the group ofpatients evaluated that day or it could be the population that isappropriate in some other respect. In any case, it is important toconsider the reference population and to have a current data set on thereference population because the predictive value would be affected bythe underlying prevalence of individuals in that particular referencegroup.

It will be appreciated that the transmission of the vascular healthinformation from the measurement device to the vascular health assessorand the transmission of the interpretation of vascular health to acommunication location can be accomplished through a variety ofcommunication links, including, modem, cable modem, DSL, Ti, andwireless transmission. The transmissions could be batch or continuous.

It will be appreciated that in a client-server informatics embodiment,some assessment functions might reside on the client side while otherswould reside on the server side, the ratio of what is placed on eachbeing a function of optimal bandwidth, computer speed and memory. Otherconsiderations include remote transmission of the data, either instepwise manner or in a batch mode, through a computational deviceattached to the ultrasound probe.

The present invention further includes a system, combined with access tothe Internet and other communication mechanisms, that providessubstantially accurate prediction of the future occurrence of vasculardisease, vascular disease diagnosis, determination of the severity ofvascular disease, and/or vascular disease prognosis. The presentinvention further provides one or more highly sophisticatedcomputer-based databases trained to interrogate, diagnose, prognose,determine the severity of and predict the future occurrence of vasculardisease, and provide increased accuracy of diagnosis and prognosis. Thepresent invention also provides a sensitive tool to assess subtledifferences in flow characteristics following exposure to substancessuch as drugs in a clinical environment.

The present invention may also be combined with a file system, such asan electronic file system, so that the individual patient's vasculardata file, the results from the analysis of vascular flowcharacteristics, may be stored in the patient file. In this manner, thehealth care provider or patient may have rapid access to information inthe patient file. Changes in vascular health since previous visits tothe health care provider may be determined quickly, thereby indicatingwhether vascular disease progression has changed or, if recommended,interventional strategies or therapeutics are effective. The presentinvention also provides physicians with the ability to rapidly advisepatients concerning recommended additional diagnostic testing andavailable treatment options following receipt of information from thecomputer-based database about the prediction of the future occurrence ofvascular disease, disease diagnosis, determination of the severity ofvascular disease, and/or vascular disease prognosis.

It is therefore an object of the present invention to provide a newmethod for assessing vascular health.

It is further an object of the present invention to provide a method forroutine evaluation of cerebral vascular health.

Yet another object of the present invention is to evaluate the vascularhealth of individuals at risk for disease.

Still another object of the present invention is to provide a method formonitoring patients who have experienced a vascular problem, such asstroke.

Another object of the present invention is to provide a method forevaluating the response of vessels to treatment(s), including conductingprocedures, carrying out therapies, and administering substances.

A specific object of the present invention is to evaluate the vascularresponse to substances in individuals at risk of cerebral vascularpathology.

Yet another object of the present invention is to evaluate the vascularresponse to treatment(s), including conducting procedures, carrying outtherapies, and administering drugs which may be used in a therapeuticmanner.

Another object of the present invention is to provide ongoing evaluationof the vascular health of patients following stroke, closed head injury,contra coup lesions, blunt force trauma, transient ischemic attacks,migraine, intracranial bleeding, arteritis, hydrocephalus, syncope,sympathectomy, postural hypotension, carotid sinus irritability,hypovolemia, reduced cardiac output, cardiac arrhythmias, anxietyattacks, hysterical fainting, hypoxia, sleep apnea, increasedintracranial pressure, anemia, altered blood gas levels, hypoglycemia,partial or complete carotid occlusion, atherosclerotic thrombosis,embolic infarction, carotid endarterectomy, oral contraceptives, hormonereplacement therapy, drug therapy, treatment with blood thinnersincluding coumadin, warfarin, and antiplatelet drugs, treatment withexcitatory amino acid antagonists, brain edema, arterial amyloidosis,aneurysm, ruptured aneurysm, arteriovenous malformations, or any otherconditions which may affect cerebral vessels. In addition, changes invascular flow following aneurysm rupture can also be monitored.

It is another object of the present invention to evaluate drugs or othersubstances suspected to have vascular activity.

Yet another object of the present invention is to evaluate drugs withsuspected vascular activity in individuals known to be at risk ofvascular disease.

Another object of the present invention is to evaluate substances, suchas drugs, suspected of having vascular activity in individuals followingstroke.

Yet other object of the present invention is to provide a non-invasivemethod to evaluate substances, such as drugs, suspected of have vascularactivity in individuals with no apparent vascular problems.

Another object of the present invention is to provide a non-invasivemethod to evaluate different dosages of substances, such as drugs,suspected of have vascular activity in individuals.

Still another object of the present invention is to provide anon-invasive method to evaluate different combinations of substances,such as drugs, suspected of have vascular activity in individuals.

Yet another object of the present invention is to provide a non-invasivemethod to evaluate different combinations of selected dosages ofsubstances, such as drugs, suspected of have vascular activity inindividuals.

A further object of the present invention is to evaluate the vascularhealth of specific vessels or vascular beds following vascular insult inanother region of the cerebral vasculature. In this manner, the capacityof other vessels to properly auto-regulate and distribute collateralblood flow may be assessed.

An advantage of the present invention is that it is not invasive.

A further advantage of the present invention is that it is rapid andinexpensive to perform.

Another advantage of the present invention is that the characteristicsof each cerebral vessel may be established as a baseline in order tomonitor the vascular health of the individual over time, especiallyduring routine physical examination, following a vascular insult orinjury, or exposure to drugs.

Yet another advantage of the present invention is that analysis ofindividual vessels and their deviation from a normal value for acorresponding vessel in another individual may indicate specific medicalconditions. Treatment of those medical conditions may then be evaluatedwith the present invention to determine whether the treatment waseffective on the specific vessel being evaluated.

Accordingly, it is an object of the present invention to provide asystem for efficient delivery of information concerning the vascularhealth of an individual.

Yet another object of the present invention is to provide a system whichhealth care providers can utilize to provide more precise and accurateprediction of the future occurrence of vascular disease, diagnosis ofvascular disease, determination of the severity of vascular disease andprognosis of vascular disease.

An object of the present invention is to provide a system which healthcare providers can utilize to provide more precise and accurateprediction, diagnosis and prognosis of vascular diseases, and associatedtreatment options, such diseases including, but not limited to,cerebrovascular disease.

It is further an object of the present invention to provide acomputer-based database that may receive vascular flow data from aninput device, interpret the vascular flow data in view of existing datafor the same vessel or vessels in normal or disease states, produce avalue(s) that provides useful information concerning vascular health andthen optionally transmit the information to another location.

It is yet another object of the present invention to provide a systemthat delivers to the health care provider a complete patient reportwithin a short time interval.

It is another object of the present invention to provide point-of-careanalytical capabilities linked through communication means to local orremote computers containing a computer-based database that may receivevascular flow data from an input device, interpret the vascular flowdata in view of existing data for the same vessel or vessels in normalor disease states, produce a value that provides useful informationconcerning vascular health, and then optionally transmit the informationto another location. Such output values may be transmitted to a varietyof locations including the point-of-care in the health care provider'soffice that transmitted results from the point-of-care flow measuringdevice. The present invention provides accurate, efficient and completeinformation to health care providers using in order to enhanceaffordable and quality health care delivery to patients.

These and other objects, features and advantages of the presentinvention will become apparent after a review of the following detaileddescription of the disclosed embodiments.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 to 4 are illustrative views showing the manner in whichultrasonic pulses are applied to the head of an individual to obtaininformation on the velocity of blood flowing in an intracranial bloodvessel;

FIGS. 5 a to 5 d provide schematic representations of transcranialDoppler ultrasound analyses in which velocity is indicated on the y-axisand time is provided on the x-axis;

FIG. 6 is a schematic representation of a 2-dimensional nomogram inwhich mean flow velocity is indicated on the y-axis and systolicacceleration is provided on the x-axis;

FIG. 7 shows the nomogram of FIG. 6, as well as areas of the nomogramwhich indicate deviations from normal, auto-regulatory conditions;

FIG. 8 shows a schematic representation of a 3-dimensional nomogram;

FIGS. 9 a to 9 d show schematic representations of a 2-dimensionalnomogram in which mean flow velocity is indicated on the y-axis andsystolic acceleration is provided on the x-axis of a patient whopresented with slight feelings of unsteadiness;

FIG. 10 is a block diagram of an illustrative system architecture of apreferred embodiment of the invention;

FIG. 11 is a concept graph of left extracranial frontal artery conceptsof a preferred embodiment of the invention;

FIG. 12 is a concept graph of left intracranial frontal artery conceptsof a preferred embodiment of the invention;

FIG. 13 is a concept graph of right intracranial frontal artery conceptsof a preferred embodiment of the invention;

FIG. 14 is a concept graph of right extracranial frontal artery conceptsof a preferred embodiment of the invention;

FIG. 15 is a concept graph of posterior artery concepts of a preferredembodiment of the invention;

FIG. 16 is a concept graph of collateral flow concepts of a preferredembodiment of the invention;

FIG. 17 is a concept graph of parameter concepts of a preferredembodiment of the invention;

FIG. 18 is a concept graph of stroke candidate concepts of a preferredembodiment of the invention;

FIG. 19 is a concept graph of small vessel disease concepts of apreferred embodiment of the invention;

FIG. 20 is a concept graph of data concepts of a preferred embodiment ofthe invention;

FIG. 21 is a concept graph of arterial condition concepts of a preferredembodiment of the invention;

FIG. 22 is a concept graph of arterial condition concepts of a preferredembodiment of the invention;

FIG. 23 is a block diagram for an application service providerarchitecture of a preferred embodiment of the invention;

FIG. 24 is an illustration of a logon page of a preferred embodiment ofthe invention;

FIG. 25 is an illustration of a user startup window of a preferredembodiment of the invention;

FIG. 26 is an illustration of a transcranial Doppler data window of apreferred embodiment of the invention;

FIG. 27 is an illustration of a hemodynamic analysis window of apreferred embodiment of the invention;

FIG. 28A depicts the global vascular status of a subject based on datafrom a number of vessel at the initial onset of symptoms associated withan increase of intracranial pressure;

FIG. 28B depicts a shift in vascular status in individual vessels as thesubject's symptoms have progressively worsened;

FIG. 28C depicts a dramatic globalized shift in vascular status ofindividual vessels after the subject's symptoms have increase to thepoint of requiring hospitalization;

FIG. 28D depicts a return of vascular status to a near normal stateafter treatment to decrease intracranial pressure;

FIG. 29 demonstrates that traditional blood flow tests would not detectthe intracranial pressure changes occurring in the subject that wereobservable using transcranial based dynamic vascular assessment;

FIG. 30 is a schematic representation of correlated MFV and SA data fromthe two series of subjects presented in Table 8;

FIG. 31 is a bar graph of Trendelenberg PI data for the two series ofsubjects from Table 8;

FIG. 32 is a schematic representation of correlated PI and SA data fromthe two series of subjects presented in Table 8;

FIGS. 33 and 34 depict 19 intracranial vessel segments available forevaluation by the invention.

FIGS. 35 a and 35 b depict the pre-stenting and post-stenting of effectsof revascularization procedures;

FIG. 36 is a plot of DWI versus DFI values following stentingprocedures; and

FIG. 37 depicts IVUS measured effects on flow at vascular regionsproximate to an area of stenosis.

DETAILED DESCRIPTION OF THE INVENTION

This application expressly incorporates herein by reference in theirentirety co-pending and commonly assigned U.S. Patent Applications Nos.09/966,368, 09/966,360, and 09/966,359, all filed on Oct. 1, 2001.

The present invention provides a novel system and method for evaluatingvascular health. This invention may be used to evaluate individuals forrisk of cerebral vascular disease. The invention may also be used forevaluating vascular health in individuals following a vascular insult orstroke. The present invention may also be used for assessing the effectsof individual substances and combinations of substances on cerebralvessels.

As noted above, the present invention comprises measurements ofparameters of vascular function. Specifically, the present inventionuses energy including, but not limited to, sound energy or any form ofelectromagnetic energy, to determine the rate of movement of cellsthrough vessels. In a preferred embodiment, ultrasound energy isutilized.

Description of Flow Data Acquisition and Analysis

According to the system and method of the present invention, anoninvasive instrument is utilized to obtain measurements of bloodvelocity in intracranial arteries and veins using Doppler principles.Since body movements such as vessel wall contractions are detected as“noise” in the Doppler signal scattering ultrasound, a high pass filteris used to reduce these low frequency, high amplitude signals. The highpass filter typically can be adjusted to have a passband above a cutofffrequency selectable between 0 and, e.g., 488 Hz.

Because not all blood cells in the sample volume are moving at the samespeed, a range or spectrum of Doppler-shifted frequencies are reflectedback to the probe. Thus, the signal from the probe may be converted todigital form by an analog-to-digital converter, and the spectral contentof the sampled Doppler signal calculated by a computer or digital signalprocessor using a fast Fourier transform method. This processing methodproduces a velocity profile of the blood flow, which varies over theperiod of a heartbeat. The process is repeated to produce a beat-to-beatflow pattern, or sonogram, on a video display. The instrument can beconfigured to analyze multiple separate frequency ranges within thespectrum of Doppler signals. Color coding may be used to show theintensity of the signal at different points on the spectral line. Theintensity of the signal will represent the proportion of blood cellsflowing within that particular velocity range. The information displayedon the video screen can be used by a trained observer to determine bloodflow characteristics at particular positions within the brain of theindividual being tested, and can detect anomalies in such blood flow,for example, the possible presence of a blockage or restriction, or thepassage of an embolus through the artery which introduces a transientdistortion of the displayed information. The instrument can also includea processing option which provides a maximum frequency follower orenvelope curve which is displayed on the video screen as the whiteoutline of the flow spectrum.

FIGS. 5 a to 5 d illustrate Doppler waveform definitions provided by asystem according to the present invention. FIG. 5 a is a graph,providing the results of a transcranial Doppler ultrasound analysis inwhich velocity is indicated on the y-axis and time is provided on thex-axis. The peak systole velocity is indicated in the Figure.

FIG. 5 b is a graph providing the results of a transcranial Dopplerultrasound analysis in which velocity is indicated on the y-axis andtime is provided on the x-axis. The end diastole velocity is indicatedin the Figure.

FIG. 5 c is a graph providing the results of a transcranial Dopplerultrasound analysis in which velocity is indicated on the y-axis andtime is provided on the x-axis. The mean flow velocity is indicated inthe Figure.

FIG. 5 d is a graph providing the results of a transcranial Dopplerultrasound analysis in which velocity is indicated on the y-axis andtime is provided on the x-axis. The systolic upstroke time oracceleration is indicated in the Figure.

The present invention provides a plot on a two-dimensional graph of thesystolic acceleration and mean flow velocity. Referring back to theauto-regulation model, one now finds that the auto-regulation curve moreaccurately describes the vascular health of a system. Addition of athird dimension, the pulsatility index, provides a three-dimensionalplot, that gives a much more accurate look at how blood is flowing inthat particular subsection of the vessel. Thus, the present inventioncombines different blood flow parameters to give a nomogram or agraphical representation of how blood is flowing within the brainitself.

The present invention permits the interrogation of cerebral vessels todetermine the state of vascular health or disease by examining the flowparameters for a vessel and comparing then with a normal value. Thisalso permits a clinical trial to be run since an entire population canbe interrogated with this relatively quick and noninvasive technique,thereby obtaining readings not only for each individual patient, butalso for the population. In addition, one can monitor the flow dynamicsof the group as a whole over time and determine if either thenon-treatment group becomes more diseased or if the treatment groupstabilizes, improves, or has a lower rate of disease, all determined byclinical measurements. Thus, the present invention provides a verysensitive blood flow interrogation tool for the brain to determinewhether a drug is going to be safe or effective for use in patients.

Using an ultrasound probe, one can determine the velocity of blood. Therelationship of the velocity of blood at two separate points within thepoints will provide the flow parameters of the present invention.Analyzing the relationship of the three parameters in each individualsegment in relationship to a normal population can determine the stateof disease of that particular segment of vessel. Further, assessing allthe segments of vessels in the brain as a whole, one can determine theinterconnections and the states of abnormal flow into whole regions ofthe brain. The more regions of the brain at risk, the higher the strokerisk for the patient. Thus, the present invention permits one toquantitate stroke risk in patients.

According to the present invention, values for various transcranialDoppler sonography measurements for a number of patients are collectedinto a database of the present invention. The database may furtherprovide ranges of transcranial Doppler sonography measurements forvarious cerebral arteries. FIG. 6 provides a nomogram of the values formean flow velocity on the y-axis and systolic acceleration on the x-axisfor transcranial Doppler ultrasound analyses of the ophthalmic artery ina number of individuals. It will be appreciated that the majority of thedata points are grouped in the lower left-hand side of the nomogram.These represent the values corresponding to vascular health. Theaberrant points found in the upper left-hand portion of the nomogramcorrespond to a state of vascular disorder, specifically, vasodilation.In addition, the aberrant points found in the lower right-hand portionof the nomogram also correspond to a state of vascular disorder;however, here these points correspond to stenosis. These observationsare provided in FIG. 7.

In another preferred embodiment, the system and method of the presentinvention permits a determination of vascular health based on ananalysis of three blood flow parameters, mean flow velocity, systolicacceleration, and pulsatility index. For example, FIG. 8 provides anomogram of the values for mean flow velocity on the y-axis, systolicacceleration on the x-axis, and pulsatility index on the z-axis fortranscranial Doppler ultrasound analyses of a cerebral artery in anumber of individuals. It will be appreciated that the majority of thedata points are grouped in a centroid located in the first octant (x>0,y>0, z>0) close to the origin of the nomogram. If plotted as thelogarithm of the value, these exhibit a normal distribution. The normalrange of the log of these values represent the values corresponding tothe vascular health of the reference population. Thus, the presentinvention permits the construction of any and all reference populationsbased on the data collected from the reference population. The data setis the ideal reference set because the reference population can bedefined in any manner, e.g., those patients who are exhibiting a certainset of symptoms or desired characteristics.

The aberrant points found distal to the origin and having a large meanflow velocity (y value) in the nomogram correspond to a state ofvascular disorder, specifically, vasodilation. In addition, the aberrantpoints found distal to the origin and having a large systolicacceleration (x value) in the nomogram also correspond to a state ofvascular disorder; however, here these points correspond to stenosis.

The measurements, gathered on a substantial number of individuals todate, demonstrate that the observed values for a normal population showstatistically normal distributions of values for the three parameters,mean blood flow, systolic acceleration, and pulsatility index.Scrutinized by means of standard multivariate statistical methods, suchas tests of significance, multivariate distances, and cluster analysis,the observed values for all three parameters all show a statisticallynormal distribution.

An aspect of a preferred embodiment of the present invention is thecollection of data by means of transcranial Doppler sonography. Asdiscussed previously, instrumentation for conducting transcranialDoppler sonography is commonly a 2 MHz pulsed Doppler and a spectrumanalyzer, in which the examiner interrogates the intracranial vesselswithout the aid of an image. Such a technique is referred to asfreehand, blind, or non-imaging transcranial Doppler sonography.Recently, duplex ultrasound systems incorporating B-mode imaging andcolor and power Doppler have been employed to perform transcranialDoppler studies. However, despite advances in duplex ultrasoundtechnology, freehand transcranial Doppler sonography is commonlyperformed because the technique can be equally accurate and theinstrumentation less expensive and more portable when compared to theduplex ultrasound.

Although freehand transcranial Doppler sonography can be characterizedas operator dependent, the technique is objective and reproducible. Theoperator, in conducting transcranial Doppler sonography, considers therelevant anatomy, natural cranial windows, and recognized examinationtechniques. Specifically, an understanding of the extracranial arterialcirculation contributing to the intracranial flow, the intracranialarterial circulation, carotid arteries, vertebral arteries, basilarartery, and their common anatomical variations is a prerequisite.

Additionally, in conducting the examination the examiner must alsoidentify the vessel. Such identification is often premised upon theacoustical window being utilized, the depth of the volume sample, thedirection of the blood flow relative to the transducer, the relativevelocity, and spatial relationships.

The examiner must also recognize that there are three acoustical windowsor regions over the cranium where the bone is either thin enough orthrough which there are natural openings to allow sufficient ultrasoundenergy to be passed into and back out of the skull to permit performanceof a transcranial Doppler examination, i.e., the signal-to-noise ratiois adequate at the “window.” However, enhanced phase array detectors mayprovide sufficiently improved signal-to-noise ratio that a “window” maynot be necessary. The three acoustical windows are the transtemporalwindow located superior to the zygomatic arch over the temporal bone;the transorbital window where the transducer is oriented directly overthe closed eyelid in a direct anteroposterior direction with a slightangulation toward midline; and the transforamenal window located midlineover the back of the neck approximately 1 inch below the palpable baseof the skull. It is to be understood that other windows may be used forother approaches using sound or other electromotive forces for detectionof cell movement within vessels. It will be recognized that many textsprovide sufficient instruction to examiners so as to enable them toperform optimal transcranial Doppler sonography. One such text is L.Nonoshita-Karr and K. A. Fujioka, “Transcranial Doppler SonographyFreehand Examination Techniques,” J. Vasc. Tech., 24, 9 (2000), which isincorporated herein by reference.

In another preferred embodiment of the present invention, ultrasoundbeam alignment is controlled rapidly and automatically in twodimensions. Devices that scan azimuth angle rapidly while varyingelevation angle in small increments have been used for 3-dimensionalimage construction, but lack speed in controlling elevation. In theanalogous area of laser scanning, it is common to steer a light beam intwo dimensions using a pair of orthogonally-rotating mirrors driven bygalvanometer movements. The double mirror approach does not work as wellwith ultrasound, however. The size and cumbersomeness of a pair ofgalvanometer driven mirrors is a disadvantage in medical applications,especially for limited space uses such as transesophageal andtransrectal probes. Another design constraint is that the wavelengths ofdiagnostic ultrasound waves are much larger than optical wavelengths, ofnecessity, since attenuation of ultrasound waves rises steeply withdecreasing wavelength. As a rule of thumb, ultrasound wavelength cannotbe much less than 1% of the maximum depth to be imaged, with an evenlarger wavelength required for imaging through tissues with highattenuation. With relatively large wavelengths, diffraction effects makeit impossible to produce very thin collimated beams that can be steeredby small mirrors, as with lasers.

For sharp focusing of ultrasound, a relatively large aperture is neededto avoid angular dispersion by diffraction. A well focused near fieldultrasound beam has the shape of a converging cone connecting to adiverging cone through a short focal neck, representing a small depth ofnear-optimum focus in the target area. Resolution approaching apractical minimum spot diameter of a little under two wavelengths at thefocus demands an included cone angle on the order of 60°. If theoriginating end of the columnar beam is made smaller while maintaining afixed focus depth, then diffraction causes the focal neck to becomethicker, sacrificing resolution at optimum depth for an increased depthrange of relatively good focus. To achieve fine focus with a doublemirror apparatus, the mirrors must be comparatively large, increasingthe difficulty of attaining fast angular response.

Typical electromechanical ultrasound image scanners employ multipletransducers on a rotating head, or an ultrasound mirror rotationallyvibrating at an angular resonance—approaches that achieve desiredazimuth scanning by sacrificing the possibility of precise angularservo-control in a non-scanning mode.

In radar, phased arrays permit rapid scanning and abrupt alignmentchanges in two dimensions from a fixed transmit/receive surface. Acomparable approach is applicable to medical ultrasound. One dimensionalultrasound phased arrays are finding increasing use, and limited controlof alignment in a second dimension is beginning to appear. In onepreferred embodiment, a stepper motor is used to rotate the scanningplane of a one-dimensional phased array through small incremental stepsin order to construct a 3-dimensional digital image. This approachrequires that the target and the ultrasound scanner be mechanicallystabilized so that frames of a slow scan are in precise registration. Aphased array with dual sets of electrodes that permit beam steering ineither of two selected scanning planes can be used. For example, asystem that employs a one dimensional ultrasound array can achievecontrollable alignment and focus depth in a plane, for use inrange-gated pulsed Doppler to characterize the flow velocity profileover the cross-section of an artery. The device is also useful toquantify angular relationships, through comparing Doppler velocities atdifferent axial locations along an artery, so that the relationshipbetween Doppler frequency shift and flow velocity can be determinedaccurately.

In many emerging ultrasound applications, visual image scanning takes ona supporting role of identifying structures and defining theirpositions, in preparation for analytic measurements in a small region,which is concerned with measuring flow velocity profiles over thedimensions of an artery and over time, to characterize volumetric flowand to detect the flow disturbances caused by stenotic lesions. Usingfixed alignment defocused beams or beams electromechanically alignedwith respect to two axes, ultrasound can be used to track thetime-varying positions of organ surfaces generating specularreflections, for the purposes of vibration tracking and diameterpulsation tracking, in a system to determine blood pressure, intraocularpressure and mechanical tissue properties. One preferred embodimentwould consist a non-focusing 2-axis ultrasound aiming device, consistingof an ultrasound transducer disk stacked on a short magnet cylinder andthe transducer-magnet pair mounted in a 2-axis gimbal bearing,consisting of pins and engaging bearing cups on the ring and the magnet,with flexible wires connecting the gimbaled part to fixed housing.Surrounding the gimbal is a torroidal ferromagnetic core in foursections, with four windings on the four 90° quadrants of the core.Opposite windings are interconnected, giving two electrical circuitsthat generate two orthogonal magnetic fields crossing the gimbaledtransducer-magnet pair. The gimbaled part tilts in response to the twoapplied fields, aiming the ultrasound beam.

In this aiming device, the axially-poled center magnet is inherentlyunstable in its center alignment, being attracted to point across thetorroid. To stabilize alignment, the torsional restoration of theconnecting wires must overcome the magnetic instability. Alignmentdirection is determined open-loop by the balance of mechanical andmagnetic forces, without direct sensing for servo-control. In anuncompensated open-loop control situation, if the net alignmentrestoration is weak, then settling is slow, and if restoration is madestronger, then the steady power needed to maintain off-center alignmentbecomes excessive. A compensated open-loop controller whose action takesinto account the known dynamic properties of a particular design, i.e.,inertia, angular spring coefficient, damping, and electromagneticcoupling strength, can speed response. The term “pole-zero compensation”is often applied to this kind of a controller, since LaPlace pole-zeroanalysis is commonly used to design the controller transfer function. Tospeed responses, the controller transfer function cancelselectromechanical low frequency zeroes with poles and low frequencypoles with zeroes, generally replacing the poles removed with new polesas far to the left of the origin as is practical within bandwidthconstraints.

Something much needed and unavailable in existing designs is fastmechanical alignment capability together with alignment sensing anderror feedback for rapid, fast settling changes in alignment. In areasof alignment tracking and analysis of echo features and their movementsor velocities, particularly for extended monitoring in unanesthetizedsubjects, there is need for a combined ability to scan rapidly for imagepresentation and to fine-tune 2-dimensional beam alignment undercontinuous software control, to maintain alignment dynamically on atissue structure subject to extended monitoring.

In the area of combined scanning and fixed beam alignment monitoring, aphased array device that switches readily between B-Mode image scanningand Doppler tracking at a specified alignment within the image plane canbe employed. A device like this, with phased array speed, can alternatebetween scanning sweeps and brief periods of Doppler data gathering at afixed alignment in a time-multiplexed mode, achieving relativecontinuity of both image and Doppler data. Electronic alignment controlis restricted to a single axis, while manual control is needed for thesecond axis. One can also employ a dual beam ultrasound device, usingone beam for tracking data from a fixed target and the other beam forongoing scanning to aid the operator in maintaining alignment on thedesired target. Again, the other axis of alignment is controlledmanually.

For many applications it is advantageous to achieve a device smallenough so that it can be affixed directly to the subject's body and ridebody motions, rather than obtaining measurements in a clinical setting.The advantages of the present invention in fulfilling these and otherneeds will be seen in the following specification and claims.

Description of Data Telemetry

The present invention provides an integrated system which combinesseveral unique technologies to assist physicians in the control,management and delivery of improved, efficient and timely medical carefor patients. Key components of this integrated system include, but arenot limited to, (1) a processor which may include, but is not limitedto, a desktop personal computer, a laptop computer, or a multi-userserver system; (2) an output device for displaying information from theprocessor, such as monitors, printers, liquid crystal displays, andother output devices known to one skilled in the art; and optionallyincluding (3) analyzers for assessing a patient's clinical profile. Suchanalyzers may be used for analyzing flow characteristics of a vessel ornumber of vessels.

All patient data may be placed in a form, such as a digitized form orother computer readable and communication acceptable form, andtransmitted to another location. In one embodiment, the computer-baseddatabase may be located in the office of the health care provider,perhaps in the computer in a physician's office. In another embodiment,the computer-based database may be located in a centralized hospitalfacility, in a emergency room/service, in a clinical chemistrylaboratory, or in a facility dedicated solely to housing and maintainingthe computer-based database. In yet another embodiment, thecomputer-based database may be located in a home computer. In a furtherembodiment, the computer-based database may be portable for uses such ason a battlefield, in rural areas and at events.

Another component in the system of the present invention includes atransmission device such as a modem or other communication device knownto one of skill in the art. Such devices include, but are not limited tosatellites, radios, telephones, cables, infrared devices, and any othermechanism known to one of skill in the art for transmitting information.The transmission device modem transmits information to the centralcomputer-based database. In a preferred embodiment, modems are used forcomputer access to the Internet. Such communication means may beessential for transmission of patient information from assessment ofvascular flow parameters, from the health care provider's point of care,such as an office, to another facility housing the computer-baseddatabase. It is to be understood that the facility housing thecomputer-based database may be located locally, in the same office, thesame building, or across town, or at a remote location such as inanother city, state, country, or on a ship, plane or satellite.

The computer-based system may be configured to take advantage of datacommunications technologies and distributed networks, which makes itpossible to deliver data to virtually anywhere in the world in anefficient and timely manner. This system in accordance with the presentinvention is capable of transferring clinical vascular flow data from aremote source to a central server via one or more networks. The centralserver hosts the computer-based database and related components.Accordingly, the central server is operable to analyze the receivedlaboratory and clinical vascular data using an expert system, in orderto produce information related to diagnoses, prognoses, decisionsupports, clinical data analyses and interpretations. The resultinginformation may then be delivered from the central server to one or moreremote client stations via one or more networks. The entire process oftransferring data from a remote source to a central server, analyzingthe data at the central server to produce information, and transferringthe information to a remote client site may thus be performed on-lineand in real time.

In automated decision support system for interpreting the values ofvarious parameters of blood flow in one or more vessels in assessing thevascular health of an individual, the data which are collected on anindividual vessel are analyzed individually for each patient and thenare also analyzed as an ensemble over that patient. In other words, allthe vessels and their respective parameters, their respective healthstates, are compared to one another and an overall system analysis ismade. The points of data in n-dimension states describing the healthstate of a vessel are tracked over time so as to determine a startingpoint and a velocity. The velocity in this case would be a direction ofchange as well as a rate of change in n-dimensional space. In moreconventional terms, if noncompliance was detected in a vessel as one ofthe dimensions in n-dimensional space, then after a treatment one mightsee that number which represents noncompliance, or a degree ofnoncompliance migrate in a certain direction—for example, towardcompliance—as the vessel becomes more compliant with the treatmentintended to make it more compliant. The significance of that change willbe assessed by looking at the velocity of health state movement indimensional space across all of the individual's cerebral vasculature.

The movement from the baseline of any single vessel point may be hard toassess for statistical significance. However, there are statisticaltools which are appropriate for analyzing the movement of the healthstates of all of the vessel points simultaneously. An example of thatwould be the Wilcox Test, which allows comparison of a group ofnon-parametric values to ascertain whether the variables arestatistically different from one another or not. Other tests may beappropriate given the data set. However, fundamentally the process is toquantitate the health state of each vessel of an individual in an-dimensional space and determine the significance of change and thedirection of change, such that if the directions and the degrees ofchange are, when considered together, significant, it can then beconcluded that the treatment is effective. In an individual case it isalso possible to stop treatment and confirm that the effect beingobserved was in fact due to the drug by observing a reversal of thesame.

When comparing a clinical trial treatment group to a control group, theprocess can be similar to what is being done with the individual. There,it is a matter of assessing whether or not the numbers quantitatingparticular characteristics of the vessel health state with regard toeach of the dimensions in dimensional space can be construed to besignificant. A discussion of the statistical analysis employed here isfound in Jerrold H. Zar, Biostatistical Analysis, Prentice Hall, Inc.N.J., pp. 153-161, which is incorporated herein by reference.

One way in which the system of the present invention is trained is onewherein the software quantitates the rationale being used by the expert.In such a system, during this process the expert and the system come tomirror each other. In the process the expert is very specific, concreteand quantitative regarding the data analysis. In its turn, the softwaremaintains a detailed bookkeeping of the analytical process. Thus, thesoftware system and the expert each begin to diversify their respectiveroles in the development of this knowledge. The purpose of the softwareis to capture the expert's analysis.

According to the expert system of the present invention, characteristicsof various functions for an automated decision support system forinterpreting the values of various parameters of blood flow in one ormore vessels in assessing the vascular health of an individual areprovided. These characteristics can be derived from various functions,for example, transcranial Doppler readings at a left anterior carotidartery or basal artery test point, flow parameters for various arteries,a summary of patient data, a summary of clinical test(s) performed on apatient, the presence of vasodilators and/or vasoconstrictors in apatient, a stenotic pattern or pattern indicating constriction of anartery at a particular test point, a vasodilation pattern or patternindicating dilation of a blood vessel, a noncompliance pattern orpattern indicating loss of compliance in an artery such as in theexample of hardening of the artery, a normal pattern or patternindicating a blood vessel with normal radius, a global vasoconstrictionor reversible stenosis of vessels in the brain, global vasodilation ordilation of all cranial blood vessels, a pseudo-normalized pattern ofconstriction or dilation at an arterial test point, a pseudo-normalizedpattern of loss of compliance in an artery, stenosis of a vessel due toblockage, dilation of an artery to compensate for loss of flowelsewhere, permanent dilation of an artery, noncompliance or a state inwhich a vessel's walls have lost flexibility, collateral flow through anartery or via reversal of flow, and/or patient risk assessment for anytype of stroke.

Parameters for determining the various functions can include, but arenot limited to, identification of the person taking the Doppler reading,the date of the reading, patient identification, a patient's sex, apatient's ethnic group, a patient's date of birth, a patient's drugusage including specific drugs, Doppler values, Doppler times,acceleration, flow direction, reading depth, the mean and/or standarddeviation of the flow velocity in a vessel, the mean and/or standarddeviation of the systolic acceleration in a vessel, the pulsatilityindex of a vessel. These parameters can be static values, inputted orretained within a database, or calculated ones. Other calculatedparameters may include the calculation of the belief of whether thereare vasodilators or vasoconstrictors present in the patient, which maybe based upon the presence of vasoactive substances such as caffeineand/or methylxanthine. An example of another calculated parameter mayinclude the belief of the severity of the constriction of an artery at aparticular test point, which may be characterized as none, minimal,moderate or severe. An example of another calculated parameter of thepresent invention may include the belief of dilation of a blood vessel,which may be characterized as none, hyperemic, normal or pathological.An example of another calculated parameter of the present invention mayinclude the belief of loss of compliance in an artery, which may becharacterized as none, normal or pathological. An example of anothercalculated parameter of the present invention may include the belief ofa blood vessel with normal radius, which may be characterized as none,hyperemic, normal or pathological. An example of another calculatedparameter of the present invention may include the belief of a bloodvessel with a high pulsatility index, or wherein the pulsatility indexof one vessel is higher than another, which may be characterized as trueor false. As can be seen from the above examples, various beliefs may becalculated according to the expert system of the present invention basedupon the function studied.

An automated decision support system according to the present inventionprovides a domain ontology for interpreting the values of variousparameters of blood flow in one or more vessels in assessing thevascular health of an individual. These parameters may be determined bymeans of a transcranial Doppler velocimetry technique, which is anoninvasive technique for measuring blood flow in the brain. Accordingto this technique, an ultrasound beam from a transducer is directedthrough one of three natural acoustical windows in the skull to producea waveform of blood flow in the arteries using Doppler sonography. Thedata collected to determine the blood flow may include values such asthe pulse cycle, blood flow velocity, end diastolic velocity, peaksystolic velocity, mean flow velocity, total volume of cerebral bloodflow, flow acceleration, the mean blood pressure in an artery, and thepulsatility index, or impedance to flow through a vessel. From thisdata, the condition of an artery may be derived, those conditionsincluding stenosis, vasoconstriction, irreversible stenosis,vasodilation, compensatory vasodilation, hyperemic vasodilation,vascular failure, compliance, breakthrough, and pseudo-normalization.

In order to best analyze a patient's risk of stroke, additional patientdata is utilized by the automated decision support system according tothe present invention. This data may include personal data, such as dateof birth, ethnic group, sex, physical activity level, and address. Thedata may further include clinical data such as a visit identification,height, weight, date of visit, age, blood pressure, pulse rate,respiration rate, and so forth. The data may further include datacollected from blood work, such as the antinuclear antibody panel,B-vitamin deficiency, C-reactive protein value, calcium level,cholesterol levels, entidal CO₂, fibromogin, amount of folic acid,glucose level, hematocrit percentage, H-pylori antibodies, hemocysteinelevel, hypercapnia, magnesium level, methyl maloric acid level,platelets count, potassium level, sedrate (ESR), serum osmolality,sodium level, zinc level, and so forth. The data may further include thehealth history data of the patient, including alcohol intake, autoimmunediseases, caffeine intake, carbohydrate intake, carotid artery disease,coronary disease, diabetes, drug abuse, fainting, glaucoma, head injury,hypertension, lupus, medications, smoking, stroke, family history ofstroke, surgery history, and so forth.

The automated decision support system according to the present inventionfurther considers related pathologies in analyzing a patient's risk ofstroke, including but not limited to gastritis, increased intracranialpressure, sleep disorders, small vessel disease, and vasculitis. In apreferred embodiment, the invention includes a decision support systemand method for screening potential participants in a drug trial. Generalreferences detailing principles and terms known to those skilled in theart of decision support systems include (1) Schank, R. C. and Abelson,R., Scripts, Plans Goals and Understanding, Hillsdale, N.J.: LawrenceErlbaum Associates (1977); (2) Schank, R. C. and Riesbeck, C. K., InsideComputer Understanding, Hillsdale, N.J.: Lawrence Erlbaum Associates(1981); (3) Sacerdoti, E. D., A Structure for Plans and Behaviors, NewYork: Elsevier (1978); (4) Rinnooy Kan, A. H. G., Machine SchedulingProblems, The Hague: Martinus Nijhoff (1976); and (5) Charniak, E.,Riesbeck, C. K. and McDermott, D., Artificial Intelligence Programming,Hillsdale, NJ: Lawrence Erlbaum Associates (1980).

Several terms used in disclosure of the present invention are describedgenerally by the following definitions accepted by those skilled in theart—

Concept Graph: a knowledge representation of the dependencies betweenobservable data values and higher level computations and assertions madeabout the data. A concept graph can be implemented as a directed acyclicgraph of concept nodes that is a particular type of augmented transitionnetwork (ATN).

Decision Support System: a computer program that uses a knowledge baseto assist in solving problems. Most expert systems use an inferenceengine to derive new facts and beliefs using a knowledge base.

Inference Engine: a computer program that infers new facts or beliefsfrom known facts or beliefs using a knowledge base and a set of logicaloperations.

Knowledge Base: a collection of knowledge (e.g., objects, concepts,relationships, facts, rules, etc.) expressed in a manner such that itcan be used by an inference engine. For example, a knowledge base mayinclude rules and facts or assertions as in traditional expert systems.

One preferred embodiment of a decision support system of the presentinvention includes the ability to assess the hemodynamic state of asubject's cerebrovasculature through the use of transcranial Dopplermeasurements. Referring to FIG. 10 the embodiment consists of threesoftware modules: a Data Access 1010 module, a Reasoning 1020 module,and a Graphical User Interface (GUI) module 1030. The Reasoning 1020module consists of two sub-modules: a situation assessment modulecomprising the PreAct DSA 1022 sub-module from Applied SystemIntelligence, Inc., including the domain knowledge base 2362; andReasoning Interface 1024 sub-module. Cognitive engines, other than DSA,may be used. The Reasoning Interface 1024 sub-module serves to hide thedetails of interacting with the DSA 1022 sub-module from other objects.In this embodiment, these modules run sequentially as part of the sameprocess, with one instance of each module.

The Data Access 1010 module provides access and storage methods for TCDmeasurement/data, clinical data, and inferences from the Reasoning 1020module. In a preferred laptop personal computer configuration thiscollection of data is stored in a file.

The GUI 1030 module processes user input to be sent to the Data Access1010 module, runs commands for the Reasoning 1020 module, queries aboutpatient data for the Data Access 1010 module, and queries aboutinference results for the Reasoning 1020 module. The GUI 1030 modulealso displays patient data received from the Data Access 1010 module andconcept instances, related to the concept graph instances received fromthe Reasoning 1020 module.

The PreAct DSA 1022 sub-module accepts leaf-level concepts representingpatient data and processes them for inferred concepts such as disease.The current concept graph may be queried for all instances of aparticular concept pattern or for evidence supporting a particularinstance. The current graph may be saved for future queries and savedconcept graphs may be reloaded for querying. The DSA 1022 sub-modulealso has access to the underlying knowledge base 2362. The ReasoningInterface 1024 sub-module accepts commands to process patient data forinferred concepts, to search for instances of particular concepts orevidence for a given concept instance in the active concept graph, andto save the current concept graph or load a saved concept graph. TheReasoning Interface 1024 sub-module converts these commands into acommand language understood by the DSA 1022 sub-module.

This preferred embodiment makes use of the data structures found inTable 1. TABLE 1 DATA DEFINITION Patient ID Uniquely identifies eachpatient Group ID Uniquely identifies each group of patients in thePatient data block Contains TCD data and clinical data for a patient.This includes: Data and measurement times for each vessel test point;Demographic data, e.g., date of birth, ethnic group; Clinical data,e.g., vital signs, test results Filename Name of a concept graph fileConcept pattern ID Unique identifier of a concept pattern Concept key IDUnique key of a concept in stance Concept instance Concept instance froma concept graph. Derived List of concept List of concept instances froma concept graph List of concept List of keys for instances of a certainpattern

Patient data consists of data derived from TCD measurements and clinicaldata. This data is used to fill in the leaf-level concepts in theconcept graph. Patient data is accessed and stored as a single block ofdata for each patient, referenced by a unique patient ID.

TCD measurements and data may be input in a streaming fashion via anetwork or direct connection or as a file. Clinical data may be input asa file or manually through the GUI 1030 module. After completing datainput, the user may elect to save the data or file for later access orto analyze the data. In either case, the Reasoning 1020 module retrievespatient data via the Data Access 1010 module. For this purpose, the GUI1030 module stores data in a file. Both modules retrieve patient data bypatient ID. Additionally, in order to allow a user to select a patient'sdata to view, edit, or analyze, the interface allows the GUI 1030 moduleto retrieve a list of all patients saved in a file. In preferredembodiments, the set of parameters passed to Data Access 1010 modulefunctions includes a user ID.

Inference data includes concept instances in the concept graph for aparticular patient. The DSA 1022 sub-module provides its own accessorsfor loading a concept graph from a text file and saving a concept graphto a text file. The Data Access 1010 sub-module is responsible forstoring the file created by the Reasoning 1020 module. Table 2identifies commands used by the Data Access 1010 module. TABLE 2 USEDCOMMAND BY PARAMETERS RETURN Initialize Module System NoneSuccess/failure layer Retrieve Patient GUI Patient ID, Patient data Datacontrol, user ID block Reasoning Save Patient Data GUI Patient ID,Success/failure control user ID Delete Patient GUI Patient ID,Success/failure Data and control user ID Concept Graph Retrieve List ofGUI User ID List of patient Patients control IDs Store Patient ReasoningPatient ID, Success/failure Concept Graph user ID, filename accessibleby Data Access Module Retrieve Patient Reasoning, Patient ID, FilenameConcept Graph GUI user ID accessible by Reasoning Module Query DatabaseGUI SQL Query Query result

The GUI 1030 module accepts input from the user, converts the user'sinput in to data and commands for other modules, and displays the valuesreturned on the screen or in a printout. The GUI 1030 module providesfor display of clinical and demographic data for a patient, raw TCD dataand measurements, and an analysis of a patient's hemodynamic state. Theanalysis of a patient's hemodynamic state includes the condition of eachartery for which TCD measurements are available, any global conditionsfound, and an assessment of the patient's risk for stroke. The GUI 1030also allows a user to drill down from a patient's risk for stroke todetermine how that conclusion was reached.

The Reasoning Interface 1024 sub-module allows other modules to accessthe concept stored in the DSA 1022 sub-module without being exposed toall the details of the DSA 1022's interface. Reasoning Interface 1024sub-module commands include those in Table 3. TABLE 3 COMMAND USED BYPARAMETER RETURN Initialize System layer None Success/failure module Runmodule GUI control Patient ID, Success/failure with a patient's datauser ID Get concept GUI control Concept List of instances pattern IDconcepts Get concept GUI control Concept Concept instance pattern ID,concept key ID Get concept GUI control Concept List of evidence patternID, concept concepts key ID Load a GUI control Patient ID,Success/failure patient's concept user ID graph Save a GUI controlPatient ID, Success/failure patient's concept user ID graph

The DSA 1022 sub-module includes methods for commanding the sub-modules,including commands for initializing, starting, running, and stopping.The DSA 1022 sub-module also includes services for setting andretrieving concept attribute values.

Requests for DSA 1022 sub-module data are responded to with one of threevalues: 1—data found correctly; O—data not found but no critical erroroccurred; and—1—critical error, see exception log file. In addition torequesting the value of a particular attribute in a known conceptinstance, the invention can request both an index of concepts and a deepcopy of a particular concept instance. The system also responds to: auser request for a list of all child concept instances of a particularconcept instance; a user request to clear all concept instances from theconcept graph (patterns will remain loaded); a user request to save aconcept graph to a specified file name (in preferred embodiments, thisfile will be saved as an XML file); and a user request to load a savedconcept graph from a specified file name.

In a broad sense, this preferred embodiment allows as user to enter newpatient data through the GUI 1030 and save the data; load existingpatient data from a database; view raw data, e.g., clinical data and TCDdata; analyze patient data for inferences about the patient'shemodynamic state; view results of an analysis; and view the evidenceused to reach a particular inference.

Upon initialization, a main program instantiates and initializes themodules and sub-modules in the following order: Data Access 1010,Reasoning Interface 1024 (which will initialize the DSA 1022), and GUI1030. After initialization is complete, control is passed to the GUI1030. Control remains with the GUI 1030 until the user signs out, atwhich point the main program shuts down the modules in the reverse orderof initialization. The Reasoning Interface 1024 module shuts down theDSA 1022.

Specific operation of the GUI 1030 module can include being initializedby one or more external commands. Operation of the GUI 1030 can furtherinclude accepting a user commands to sign in to the system; change thegroup of patients currently being processed (contingent upon authorityof that user to have access to the data for the new group); create a newgroup; sign out of the system; create a new patient record; process apatient's data for inferences; edit data for a new or existing patient;save a patient's data; display a list of subjects in the specified group(including an indication of whether or not a hemodynamic analysis hasbeen done on the patient's data; display patient data for an existingpatient; display patient's overall risk of stroke; display anexplanation of a patient's stroke risk, including concepts used asevidence and the ability to drill down in to evidence for furtherdetailed display; and display the status of arterial flow in all thepatient/subject's arteries for which data is available, including flowcharacteristics at each test point, global characterizations of bloodflow, and the direction of blood flow.

Specific operation of the Data Access 1010 module can include serving asan interface to an existing relational database management system;accepting commands for initialization, shutdown, creation of a newpatient record, retrieval of the patient data block for a specifiedpatient, update of a patient's data, deletion of a record, retrieval ofa concept graph, update of a concept graph, deletion of a concept graph;and accepting a query for a list of all patients in the database.

Specific operation of the Reasoning Interface 1024 sub-module caninclude initialization by one or more external commands; acceptingcommands for processing a patient's data, saving the analysis of thecurrent patient's data, loading a saved analysis, and stop processing;and accepting queries for instances of particular concept patterns inthe concept graph, a particular concept instance, and furtherexplanation of a concept instance.

Specific operation of the DSA 1022 sub-module can include initializationby one or more external commands; and use of knowledge bases to storeconcept patterns and knowledge base algorithms used to infer conceptsfrom leaf-level data provided, with the basis for the inferences beingthe TCD data and clinical data. The algorithms infer the concepts inseveral intermediate steps, each represented in the concept graph, suchthat it is sufficient for one skilled in the art of the problem domainto follow the chain of reasoning. The conditions represented in theconcept graph include, but are not limited to, vasodilation, hyperemicvasodilation, pathological vasodilation, non-compliance, andirreversible stenosis. The concept graphs provide a path for following achain of reasoning backwards from a conclusion. The algorithms use aplurality of reasoning techniques, e.g., Bayesian reasoning, to look forsupporting data in related concepts. Further operation of the DSA 1022sub-module can include loading knowledge bases; accepting patient datato be processed through transactions; allowing the user to save theconcepts resulting from an inference and load saves concepts; andquerying for instances of particular concept patterns in the currentconcept graph, particular concept instances, and further explanation ofa concept instance. This querying can include accepting a clear command,and in response, clearing all concept instances from the current graph;concept patterns remain loaded; accepting a kill command to release allallocated memory and terminate; and writing non-fatal errors to a logfile.

In another preferred embodiment, the invention is a networked basedsystem and method for analyzing the hemodynamic state of a subject basedon TCD measurements. When using this embodiment, a user submits data toa centralized system for analysis similar to that described in theprevious embodiment.

Referring to FIG. 23 a block diagram illustrating the context andrelationship between modules for the preferred Application ServiceProvider (ASP) embodiment is shown. The modules run in separate processspaces. The user interface (one or more instances of a Web Browser 2310)and System Interface 2320 are connected via a network, in this case theInternet, using connection protocols known to those skilled in the artof computing. The System Interface 2320 Manager provides an adaptivelayer between the web server and the remainder of the system. TheAccounts Manager 2340 maintains authorization and accounting data foreach user account. The Reasoning Manager 2350 manages requests foranalysis of data and queries of existing analyses. It also maintainsconnections to one or more instances of the Reasoning Module 2360. TheReasoning Module 2360 encapsulates a DSA component in a fashion similarto the earlier described embodiment. The DSA component uses theinvention's knowledge base to analyze TCD data and provide access toresults. The Reasoning Module 2360 provides translations to and from theinterface language use by the DSA component. The Watchdog 2370 monitorsinvention performance for functioning within acceptable parameters.

The invention is accessed via the Internet through a web site, using astandard browser 2310. FIGS. 24 through 27 illustrate the data availablethrough typical pages displayed at the browser in response toappropriate user actions. The system is entered through a login page, anexample of which is illustrated in FIG. 24. In this embodiment, the samelogin page is used by both users and administrators. Based on theidentity of the account, the invention will present either theadministrator startup page or the user startup page. The administratorstartup page provides an administrator with access to administrationfunctionality described below. The user startup page, illustrated inFIG. 25, lists those patients that are associated with the user. Fromthis point, the user may add new patient data, edit existing patientdata or delete patient data.

The patient data page, illustrated in FIG. 26, displays clinical data ona patient and allows a user to edit this data. The patient data pagealso provides access to the TCD data tab for that patient. The TCD datatab for a patient, provides access to TCD measurements. The user may addnew TCD measurements, view existing measurements, edit, or deletemeasurements. This page provides further access to the hemodynamicanalysis tab, illustrated in FIG. 27, for the patient. The hemodynamicanalysis tab displays the result of an analysis of a patient's TCD data.If no analysis has been performed on a set of TCD readings, the user mayrequest that such analysis be performed from this page.

The Knowledge base 2362 maintains the knowledge for TCD analysis. Theinventions analytical techniques may be modified by changing theseKnowledge base 2362 files. The Patient database 2382 stores data about apatient pertinent to analysis of his TCD data. Each patient is assigneda unique ID by the user of the system. Information contained in thePatient database 2382 includes that shown in Table 4. TABLE 4 ITEMDESCRIPTION User ID Unique identifier for the user of the system PatientID Unique identifier for this patient within this user's patients Dateof birth Patient's date of birth Sex Patient's generic sex Ethnic groupPatient's ethnic group For each set of TCD readings for this patient:Reading date Date of reading For each reading within a set of TCDreadings Segment ID Arterial segment from which the reading was takenDepth Depth of the reading (mm) PSV Peak systolic velocity PSVTimeTimestamp of PSV reading (sec) EDV End diastolic velocity EDVTimeTimestamp of EDV reading (sec)

The Patient Analysis Database 2384 stores the Reasoning 1020 module'sanalysis of a set of TCD data. The analysis is stored as a file in aformat that can be read into the Reasoning 1020 module, e.g., anextensible Markup Language (XML) file. Information contained in an entryin the Patient Analysis Database 2384 includes the information in Table5. TABLE 5 ITEM DESCRIPTION User ID Unique identifier for the user ofthe system Patient ID Unique identifier for this patient within thisuser's patients Reading Patient's date of birth Analysis Output filefrom the patient's concept graph

The Authorization Database 2342 stores the IDs and passwords ofauthorized users and administrators. Information contained in an entryin the Authorization Database 2342 includes the information in Table 6.TABLE 6 ITEM DESCRIPTION User ID Unique identifier for the user of thesystem Password Encrypted password for the user Account User orAdministrator

The Transaction Log 2344 records activity of users and administrators inthe system, Information contained in the Transaction Log 2344 includesthe types found in Table 7. TABLE 7 TRANSACTION NAME TRANSACTION FIELDSLog in User ID Timestamp Failed log in User ID Invalid passwordTimestamp Log out User ID Timestamp Add new patient User ID Patient IDTimestamp Edit patient data User ID Patient ID Timestamp Delete patientUser ID Patient ID Timestamp Analyze patient User ID Patient ID ReadingID Timestamp Display patient list User ID Timestamp Display patient UserID Patient ID Timestamp Create new account Administrator ID New accountID Account type (user or administrator) Timestamp Delete accountAdministrator ID Account ID Timestamp Download Transaction AdministratorID Log Timestamp Download Authorization Administrator ID DatabaseTimestamp Timestamp

System Database 2390 stores data used to provision the application'sprocess. Examples include parameters for the IPC connections and thelocation of the data files specified in the above description.

Knowledge structures are defined and developed over the lifecycle of theinvention; both for this embodiment and for other preferred embodiments.The knowledge structures identify broad functionality to envision theinvention's behavior. Preferred embodiment of the present invention usea concept graph (CNG) for knowledge representation. The CNG, see FIGS.11 through 22, contain input data to the system and inferred states formthe input data. Arrows in the concept graph represent the direction ofinference. The inferences culminate in the top-level Stroke Riskconcept.

The system provides various functionality to authorized users, includinglogging in using an existing account; setting up a new patient record;editing an existing patient record; requesting and obtaining an analysisof a previously entered set of patient TCD readings; requesting andobtaining a list of all patients for which that user has entered data,with the existence of an analysis indicated; requesting and obtaining adisplay of previously entered data and, if available the analysis ofthat data; deleting patient data entered by that user; deleting a TCDreading set; and logging off.

The system provides various functionality to authorized systemadministrators, including logging in; creating a new account; listingall existing accounts; deleting an existing account; downloadingtransaction data; changing the e-mail address to which notifications aresent by the Watchdog 2370; and logging off.

Upon initialization, a main program instantiates and initializes themodules in the following order: Watchdog 2370, System Interface 2320,Accounts Manager 2340, Data Manager 2380, Reasoning Manager 2350. Thesemodules run in separate process spaces from the main program. Uponshutdown, a main program shuts down the modules in the following order:Reasoning 1020 module, Data Manager 2380, Accounts Manager 2340, SystemInterface 2320, Watchdog 2370.

The System Interface 2320 is initialized by external command. Itconverts data submitted in hypertext markup language (HTML) intocommands for other system modules, and conversely, reformats data fromother system modules into outbound HTML pages for presentation to auser. The System Interface 2320 module maintains a list of userscurrently logged into the system and automatically logs a user off aftersome time of inactivity. The System Interface 2320 accepts a shutdowncommand accepts requests for system data from other modules.

The Data Manager 2380 can be initialized by an external command, andmaintains data in persistent storage. The Data Manager 2380 is able toaccept and respond to various commands, such as retrieve the IDs ofpatients entered by a particular user; set up a new patient record;retrieve a patient's data; modify a patient's data; store the analysisof a particular TCDV reading; retrieve the analysis of a particular TCDVreading; delete a patient's records; and shut down.

The Accounts Manager 2340 can be initialized by external command, andcan accept transactions to be recorded in a Transaction Log 2344. TheAccounts Manager 2340 can accept and respond to commands such as createa new account; delete an existing account; validate an account ID andpassword (if the account ID and password are valid, the Accounts Manager2340 can indicate in the reply whether this account is a regular user oran administrator); download the Transaction Log 2344; download theAuthorization Database 2342; and shut down.

The Reasoning Manager 2350 can be initialized by an external command.Upon initialization, the Reasoning Manager 2350 initializes one instanceof the Reasoning 1020 module. The Reasoning Manager 2350 maintainsconnections to all existing instances of the Reasoning 1020 module. TheReasoning 1020 modules run in a separate process space from theReasoning Manager 2350. The Reasoning Manager 2350 initialize additionalinstances of the Reasoning 1020 module or delete instances of theReasoning 1020 module as necessary to optimize the system load.

The Reasoning Manager 2350 is able to accept and respond to variouscommands such as analyze a patient's data. The patient's data is assumedto be accessible through the Data Manager. The Reasoning Manager 2350retrieves the data from the Data Manager, loads it into a particularReasoning 1020 module, and issues a command to the Reasoning 1020 moduleto analyze the data. The Reasoning Manager 2350 is further able toaccept and respond to other various commands such as query a patient'sanalysis for a particular concept instance. In this instance, theReasoning Manager 2350 loads the analysis into a Reasoning 1020 module,if necessary, and sends a query to the Reasoning 1020 module. TheReasoning Manager 2350 is further able to accept and respond to othervarious commands such as query a patient's analysis for all instances ofa particular concept pattern. In this instance, the Reasoning Manager2350 loads the analysis into a Reasoning 1020 module, if necessary, andsends a query to the Reasoning 1020 module. The Reasoning Manager 2350is further able to accept and respond to other various commands such asquery a patient's analysis for further explanation of a conceptinstance. If necessary, the Reasoning Manager 2350 loads the analysisinto a Reasoning 1020 module and sends a query to the Reasoning 1020module. The Reasoning Manager 2350 is further able to accept and respondto other various commands such as shut down. When shutting down, theReasoning Manager 2350 preferably shuts down all instances of theReasoning 1020 module.

Reasoning 1020 module is initialized by an external command. No othercommands are processed until the module is initialized. The Reasoning1020 module Applied System Intelligence, Inc.'s PreAct DSA 1022 moduleto store and analyze data using a concept graph. The Reasoning 1020module uses a knowledge bases independent of the PreAct library to storethe concept patterns and necessary algorithms. These knowledge base 2362s are loaded after the module is initialized. The algorithms use variousreasoning techniques, e.g., Bayesian reasoning, to propagate beliefvalues through the graph. Sample concept graphs can be found at FIGS. 11through 22. The Reasoning Module 2360 provides accessors to inputpatient data into the concept graph.

The Reasoning Module 2360 accepts and responds to various commands suchas clear the current concept graph; analyze a patient's data(preferably, the module sends a notification when the analysis iscomplete); save the analysis of the current patient's data (preferably,the module sends a notification when the save is complete); load a savedpatient analysis; and stop.

The Reasoning 1020 module can accept and respond to one or more queriesfor all instances of a particular concept pattern in the concept graph;a particular concept instance; and further explanation of a conceptinstance. The Reasoning 1020 module is further able to write non-fatalerrors to a log file.

The Watchdog 2370 includes an off-the-shelf module chosen to beinitialized by an external command which will set all necessaryparameters; to send a notification to a specified set of e-mailaddresses when the available disk space drops below a preset level; tosend a notification to a specified set of e-mail addresses when thesystem load exceeds a preset level; and to accept and respond to acommand to change the set of e-mail addresses to which notifications aresent.

An exemplary network architecture of an exemplary system in accordancewith the present invention is described below. The exemplary systemcomprises one or more client stations, a central server and acommunications link. The one or more client stations function as remoteaccess points to the central server. A client station may be located ina laboratory, a physician office and/or at any other appropriate site. Aclient station may be configured for transmitting and/or receivinginformation to or from the central server in either an interactive modeor a batch mode.

Client stations may comprise any type of computer-like device that iscapable of sending and/or receiving data. For example, a client stationmay comprise a desktop computer, a laptop computer, a hand-held device,or the like. A client station may also comprise a laboratory instrumenthaving functionality for collecting raw data (such as patient vasculardata), and for transferring that raw data to the central server via thecommunications link. A client station may also comprise a device forreceiving raw data from a laboratory instrument, such as a flowanalytical device, or a device holding data transmitted from a flowanalytical device, and then passing that data to the central server viathe communications link. These and other examples of client stationconfigurations will be apparent to those of ordinary skill in the art.

A first client station may be configured to transmit raw data to thecentral server via the communications link and a second client stationmay be configured to receive processed data (results) from the centralserver via the communications link. A client station may implementvarious user interfaces, printing and/or other data management tasks andmay have the ability to store data at least temporarily.

The communications link may comprise a dedicated communications link,such as a dedicated leased line or a modem dial up connection.Alternately, the communications link may comprise a network, such as acomputer network, a telecommunications network, a cable network, asatellite network, or the like, or any combination thereof. Thecommunications link may thus comprise a distributed network and/or oneor more interconnected networks. In an exemplary embodiment, thecommunications link may comprise the Internet. As should be apparent tothose of skill in the art, the communications link may be land-linebased and/or wireless. Communications over the communication linkbetween the client station and the central server may be carried outusing any well-known method for data transmission, such as e-mail,facsimile, FTP, HTTP, and any other data transmission protocol.

The central server comprises the computer-based database of vascularinformation. The central server implements analytic and interpretivealgorithms. It will be apparent to those of skill in the art, however,that the communication station and the computation station may beimplemented in a single computer. The configuration of an exemplarycentral server will be described in greater detail below.

A system in accordance with an exemplary embodiment of the presentinvention may operate in an interactive mode or a batch mode. In theinteractive operating mode, data samples are processed one by oneinteractively. For example, in an interactive processing mode, a userconnects to the central server through a client station. A data sampleto be processed is then sent from the client station to the centralserver. The processed data (result file) is returned from the centralserver to the client station, where it may be printed and/or archived.After the result file is received at the client station, a subsequentdata sample may then be transmitted from the client station to thecentral server.

An exemplary system configured for an interactive processing mode is nowdescribed. A client station may be configured for execution of acommunication browser program module and one or more printing and/orarchiving program modules. As is known in the art, a convenient andeffective communication link for facilitating interactive operations isthe Internet. Communication browsers are also known as World Wide Webbrowsers or Internet browsers.

The components of the central server may be distributed among twostations, a communications station and a computation station. Configuredfor an interactive processing mode, the communications station maycomprise a communications server, such as a standard http server, forinteracting with the communication browser executed at the clientstation. Communications between the communications server and thecommunication browser may occur using html pages and computer graphicsinterface (CGI) programs transferred by way of TCP/IP.

Substances

In one preferred embodiment of the present invention, vascularreactivity to substances may be evaluated. Substances include, but arenot limited to, alcohol, nicotine, foodstuffs, extracts of plants,nutraceuticals, and drugs. Many drugs are known to have effects on thevascular system. A non-limiting list of classes of drugs and drugs knownto have affects on the vascular system includes the following: betaadrenoreceptor antagonists; calcium channel antagonists; angiotensin Iconverting enzyme inhibitors; alpha adrenoreceptor antagonists;cholesterol antagonists; angiotensin II 1 antagonists; HMGCoA reductaseinhibitors; thrombin inhibitors; adrenoreceptor antagonists; endothelinA receptor antagonists; NMDA antagonists; platelet aggregationantagonists; NMDA antagonists; platelet aggregation antagonists; sodiumchannel antagonists; 5-hydroxytrypltamine 1a agonists; AMPA receptorantagonists; GPIIb IIIa receptor antagonists; lipase clearing factorstimulants; potassium channel agonists; potassium channel antagonists;5-alpha reductase inhibitors; acetylcholine agonists; dopaminergicagonists; endopeptidase inhibitors; estrogen antagonists; GABA receptoragonists; glutamate antagonists; peroxisome proliferator-activatedreceptor agonists; plasminogen activator stimulants; platelet-derivedgrowth factor receptor kinase inhibitors; prostacyclin agonists;sodium/hydrogen exchange inhibitors; vasopressin 1 antagonists;15-lipoxygenase inhibitors; acetyl CoA transferase inhibitors; adenosineA1 receptor agonists; aldose reductase inhibitors; aldosteroneantagonists; angiogenesis stimulants; apoptosis antagonists; atrialpeptide antagonist; beta tubulin antagonists; bone formation stimulantscaspase inhibitors; CC chemokine receptor 2 antagonists; CD 18antagonists; cholesterol ester transfer protein antagonists; complementfactor inhibitors; cyclooxygenase inhibitors; diuretics; DNAtopoisomerase ATP hydrolyzing inhibitors; elastase inhibitors;endothelial growth factor agonists; enkephalinase inhibitors; excitatoryamino acid antagonists; factor Xa inhibitors; fibrinogen antagonists;free radical scavengers; glycosylation antagonists; growth factoragonists; guanylate cyclase stimulants; imidazoline I1 receptoragonists; immunostimulants; immunosuppressants; interleukin 1-betaconverting enzyme inhibitors; interleukin 8 antagonists; LDL receptorfunction stimulants; MCP-1 antagonists; melanocortin MC-4 antagonists;mineralocorticoid antagonists; nerve growth factor agonists;neuropeptide Y antagonists; oxygen scavengers; phosphodiesteraseinhibitors; potassium sparing diuretics; proline hydroxylase inhibitors;prostaglandin E1 agonists; purinoreceptor P2T antagonists; reducingagents; thromboxane A2 antagonists; thyroid hormone function agonists;transcription factor inhibitors; vasopressin 2 antagonists; andvitronectin antagonists, among others.

In addition, other agents are suspected of having vascular activity.These agents are include, but are not limited to, danaparoid sodium,nitric acid scavengers, clomethiazole, remacemide, TP10, cerivastatin,nimodipine, nitrendipine, BMS-204352, BIII-890, dipyridamole+ASA,fradafiban, irampanel hydrochloride, lefradafiban, aptiganel,sipatrigine, NRTs, cromfiban, eptifibatide, nematode anticoagulantprotein NAPc2, UK-279276, Flocor, DMP-647, ASA, GPI-6150, dermatansulfate, NOS inhibitors, ancrod, PARP inhibitors, tinzaparin sodium,NOX-100, LDP-01, argatroban, fosphenyloin, tirilazad mesylate,dexanabinol, CPC-211, CPC-111, bosentan, clopidogrel hydrogen sulfate,nadroparin, ticlopidine, NS-1209, ADNF III, vinconate, ONO-2506,cilostazol, SUN-N4057, SR-67029i, nicardipine, YM-337, and YM-872.

The present invention may be utilized following administration of thedrug through acceptable methods of administration to evaluate theeffects on vessels. It is to be understood that the present inventionmay be practiced with regard to different vessels, including but notlimited to, vessels in the extremities, in the coronary circulation, andextracranial and intracranial cerebral vessels. In a preferredembodiment, the extracranial and intracranial cerebral vessels areexamined with the present invention.

Measurements may be taken before administration of the drug, and atspecific times following administration of the drug to determine theeffect of the drug on vascular reactivity. In this manner, eachindividual subject and each individual vessel acts as its own control toassess the effects of that drug on that specific vessel.

All cerebral vessels may be analyzed to determine whether the drug hasdifferential effects on different cerebral vessels. By performing suchan analysis over numerous individuals, valuable data may be obtainedconcerning the vascular effects of a specific drug. Furthermore, bychoosing individuals from different groups, such as (a) individuals withno known pathology, (b) individuals with no known pathology in specificage groups, (c) individuals with known pathology in a specific diseasegroup, (d) individuals with known pathology in a specific disease groupin a specific age range or in a specific stage of the progression of thedisease, and (e) individuals in a specific disease group currentlyreceiving specific therapeutic mediations.

Through application of the present invention to individuals from thedesired group, valuable information may be obtained concerning theeffects of different disease processes, or prior or co-administration ofother drugs, on the vascular effects of the test drug in differentindividuals, at different ages, and in different conditions.

It will be appreciated that a preferred embodiment of the presentinvention allows for the assaying of the efficacy of a treatmentcomprising collecting data regarding cerebrovascular health status of anumber of individuals serving as patients in the clinical trial;grouping the patients into at least two groups of patients such thatpatients with a similar cerebrovascular health status are groupedtogether; applying the treatment to the at least two groups of patients;monitoring outcomes of the treatment for each of the at least two groupsof patients; and determining the efficacy of the treatment based on theoutcomes of the treatment for each of the at least two groups ofpatients. In a preferred embodiment of the present invention, the dataregarding cerebrovascular health status comprises mean flow velocityvalue for at least three cerebrovascular vessels of the individuals andsystolic acceleration value for at least three cerebrovascular vessel sof the individuals. In another preferred embodiment of the invention,the data regarding cerebrovascular health status further comprisescalculating a pulsatility index.

Another preferred embodiment of the present invention provides a methodof screening for adverse effects of a treatment comprising: applying thetreatment to a number of individuals; monitoring the cerebrovascularblood flow of such individuals after applying the treatment; andidentifying adverse effects to cerebrovascular blood flow in suchindividuals arising after applying the treatment. In a preferredembodiment, quantitative data regarding the cerebrovascular blood flowof a number of individuals is obtained. In a still further preferredembodiment of the present invention, the data regarding cerebrovascularhealth status comprises mean flow velocity value for at least threecerebrovascular vessels of the individuals and systolic accelerationvalue for at least three cerebrovascular vessels of the individuals. Instill a further preferred embodiment, the data regarding cerebrovascularhealth status further comprises calculating a pulsatility index.

It will be appreciated that the present invention allows for thecreation of matched groups with a suite of blood vessel issues, e.g.,plaque and general vasculitis, among others. The present invention alsoprovides for the creation of matched groups with a particularcirculatory problem, e.g., stenosis in a particular vessel, inadequateprofusion of small blood vessels in posterior of brain, migraines, andapnea, among others.

Under conventional approaches to clinical trials, one cannot identifyparticipants with such problems, much less match participants whereinboth groups have essentially the same severity and incidence of thepathology being examined. Thus, the conventional approach to clinicaltrials (1) address much less specific conditions, e.g., overall strokerisk, rather than the precise severity and incidence of the pathologybeing examined, (2) include individuals who show nodisease/deterioration, and (3) include individuals who are likely tosuffer immediate catastrophic failure. Despite numerous attempts toconduct clinical trials related to primary stroke prevention where thereis no previous history of stroke or acute cardiac event, this problemhas remained unsolved until now.

EXAMPLE 1

Effects of Propranolol on Vascular Reactivity

Propranolol, also known as Inderal, is prescribed routinely forindividuals with hypertension, one of the major risk factors for stroke.In order to assess the effects of propranolol on vascular reactivity, atranscranial Doppler analysis was performed on the cerebral vessels of a46 year old hypertensive man. Propranolol was then administered at anoral dosage of about 40 mg. Another transcranial Doppler analysis wasperformed approximately two hours after administration of thepropranolol. Changes in specific vessels were compared topre-administration readings. By analyzing pre- and post-administrationvessel dynamics, an indication of the effect of the beta adrenergicblocker, propranolol, on dynamics of flow in specific cerebral vesselsis obtained.

EXAMPLE 2

Analysis of the Effects of Plavix on Cerebral Vessels

Plavix is a member of a class of drugs known as blood thinners oranti-platelet drugs. Plavix is often prescribed following stroke tominimize platelet aggregation and clot formation. However, one of themajor dangers of Plavix is intracranial hemorrhage. Therefore, whenusing Plavix to prevent or minimize the possibility of a stroke due toinfarction, one may increase the possibility of a hemorrhagic stroke.Accordingly, properly selecting the appropriate patient for Plavix iscritical for maintenance of vascular health.

A 63 year old male with a history of hypertension experiences a firststroke in the left middle cerebral artery resulting in deficits in theright hand, leg, and some deficits in motor speech. These are thesymptoms upon presentation in the neurological clinic. TranscranialDoppler analysis of all cerebral vessels is performed in addition toanalyzing the common carotid artery and the internal carotid artery. Theanalysis reveals alterations in vascular flow in the internal carotidartery just distal to the bifurcation of the common carotid artery. Astenotic area is observed. Further, additional flow abnormalities aredetected in the left middle cerebral artery, consistent with thepatient's presentation of right-sided motor paralysis. TranscranialDoppler analysis reveals excellent collateral flow to the contralateralhemisphere and no deficits in the left anterior cerebral and leftposterior cerebral arteries.

The physician considers prescription of Plavix together with a calciumchannel blocker. Transcranial Doppler analysis was performed at monthlyintervals. By analyzing changes in the individual cerebral vessels as afunction of Plavix +/− calcium channel blocker administration, thephysician observes no effect on the cerebral vessels. The physiciansubsequently administers a higher dose. Again, transcranial Doppleranalysis is performed on all cerebral vessels. The physician observesmarked changes in the vascular dynamics of the vessel studied as thepulsatility index decreases and the auto-regulation curve left-shiftstoward normal. The physician, based on these results, determined aproper dosage of the vasoactive medication for the patient.

The patient is then monitored on a monthly basis after the initialprescription of Plavix in order to determine whether vascular changesare occurring which necessitate alteration in the therapy.

EXAMPLE 3

Assessment of Cerebral Vascular Status During Battlefield Situations

A 21 year old paratrooper jumps from an airplane to reach thebattlefield below. While parachuting to the surface, his parachutebecomes entangled in the branches of a large tree. The serviceman hearsgunfire in the vicinity of his location and, in an attempt to freehimself, cuts one of the lines connecting the parachute to his harness.He falls to the earth but his head strikes a major branch of the treeduring descent. The serviceman is found unconscious by a field medic.After determining that no cervical fracture is present, the medicremoves the serviceman to a field hospital. Transcranial Doppler isperformed by the medic trained in such techniques. The data is acquiredand transmitted by an uplink satellite communication to a battlefieldcommand center hospital. Prior data on the serviceman is compiled duringroutine physical examination at the time of induction into the service.The new transcranial Doppler data is compared to the prior data. Theresults indicate dramatic changes in auto-regulation of the leftanterior cerebral artery. This is caused by vasospasm due to asubarachnoid hemorrhage from blunt force trauma at the fronto-parietalsuture. There is also a subdural hematoma. The field physician suspectsthis possibility in view of the contusions evident in the region of thissuture. The results of the comparative analysis of the cerebral vesselsare transmitted to the field physician who then performs an emergencycraniotomy in the region of the left fronto-parietal suture. Followingrelease of pressure on the brain and stabilization of the patient, atranscranial Doppler analysis is performed immediately post surgery, andat 12 and 24 hours thereafter. The results indicate that the leftanterior cerebral artery flow dynamics are changing and thecharacteristic of this vessel moves from the lower right quadrant on theplot of flow velocity versus systolic acceleration toward the region ofnormal auto-regulation.

Another scenario is development of spasm or post-traumatic hyperemia at24° C. with clinical deterioration. Transcranial Doppler analysis wasperformed at the field hospital. Worsening vasospasm was found and thetreatment altered in response.

EXAMPLE 4

Application of Transcranial Doppler Analysis in the Emergency Room

A 23 year old is admitted into the emergency room in a state of extremeagitation and mania. While the medical staff is attempting to obtain ablood workup and waits for the results of the analysis, the patientsuddenly falls unconscious. Blood pressure is observed to dropprecipitously. Transcranial Doppler analysis is performed on thecerebral vessels of the patient. The results indicate a shifting to thelower left of the normal regulation curve for the left middle cerebralartery. Electrocardiagraphic analysis reveals atrial fibrillation. Bloodchemistry reveals that the patient took a large dosage of cocainetogether with amphetamine. The results of the transcranial Doppleranalysis are consistent with induction of cerebral vascular failurewhich was secondary to a heart attack due to extreme vessel constrictionof the coronary vasculature.

EXAMPLE 5

Case Study of a Female Who Presented With Unsteady Gait

A 62 year old female presented in the neurological clinic complaining ofslight feelings of unsteadiness during walking. Transcranial Doppleranalysis was performed and the different cerebral vessels were analyzed.The initial nomogram schematic representation of a 2-dimensionalnomogram of the transcranial Doppler sonography data, in which mean flowvelocity is indicated on the y-axis and systolic acceleration isprovided on the x-axis, is provided in FIG. 9 a. Shortly thereafter, thepatient's symptoms worsened, however, no definitive diagnosis was yetestablished. Transcranial Doppler analysis was performed a second timeand the transcranial Doppler sonography data was represented in a secondnomogram provided in FIG. 9 b. The results were compared to the firsttest and showed a clear shifting to the right on the flow velocityversus systolic acceleration plot.

Next, the patient was hospitalized in critical condition and yet nodiagnosis had been established. The technician performed anothertranscranial Doppler test and the transcranial Doppler sonography datawas represented in a third nomogram provided in FIG. 9 c. A dramaticshifting to the right of many of the vascular points was observed. Acisternogram revealed hydrocephalus, so a shunt was inserted. Theneurologist concluded that an increased intracranial pressure hadexerted a deleterious effect on the cerebral vessels displacing themfrom the normal auto-regulation zone. Following surgery, a fourthtranscranial Doppler analysis was performed and the transcranial Dopplersonography data was represented in a fourth nomogram provided in FIG. 9d. The results showed a clear return toward baseline, i.e., a leftshifting in the characteristic data points for the vessels analyzedtoward their prior location at the time of the second test.

This example demonstrated that the results from the transcranial Doppleranalysis, a non-invasive and highly accurate test, provided valuableinformation for the neurologist to select an appropriate course ofaction thereby probably preventing a massive increase in intracranialpressure resulting in an occlusive stroke and probable death. Theseresults also provided an indication of the onset of the life-threateningchanges that occurred between tests 2 and 3.

EXAMPLE 6

Use of Transcranial Doppler to Analyze Blunt Force Trauma in an Athlete

During a soccer match, a 17 year old high school student receives asevere blow to the forehead when he and an opponent jumped together tohead the ball. The student becomes unconscious but is then revived withsmelling salts. After the game, he complains of changes in his vision.He is taken to the emergency room and a transcranial Doppler analysis isperformed. The results of the analysis are compared to a transcranialDoppler analysis performed at the beginning of the soccer season.Transcranial Doppler analysis shows a slight change in the flow dynamicsof the left posterior cerebral artery indicating hyperemia or increasedflow often observed in patients with cerebral contusions. Twenty-fourhours later the patient's mental state deteriorates and a CT scan onlyreveals subarachnoid blood. A repeat transcranial Doppler analysis showsvasospasm of the same artery. An interventional neuroradiologist iscalled into the case and performs angioplasty. Following the procedure,transcranial Doppler analysis is performed periodically over a 6 weekperiod. The results are compared to the transcranial Doppler profile atthe time of admission to the emergency room and also to the normalreadings obtained at the beginning of the soccer season. The resultsshow a gradual return to the normal flow patterns for the left posteriorcerebral vessel.

EXAMPLE 7

Use of Transcranial Doppler to Analyze Blunt Force Trauma in theVascular Effects of a Drug

A pharmaceutical company has developed a new substance which it suspectsmay have antihypertensive activity by inducing partial dilation of bloodvessels. The company selects a patient population of individuals withnormal blood pressure, a population with mild hypertension, and apopulation with severe hypertension. Sub-populations are constructedbased on age (fourth, fifth and six decades of life) and sex.

The cerebral vessels of all patients are analyzed using transcranialDoppler analysis, as described in the present invention, two hoursbefore and two hours following oral administration of 25 mg of the testsubstance. Blood pressure was monitored at 30 minute intervals for thetwo hours before and two hours following oral administration of the newsubstance. The results demonstrate no discernable effect in thenormotensive and mildly hypertensive group, and a significantanti-hypertensive effect in the severely hypertensive patients in allage groups tested. Analysis of the data obtained with transcranialDoppler revealed a decreased flow velocity in the vessels of the greatarterial circle.

Significant variation is detected in the data set from the female testgroups in the fifth and sixth decades of life. Further questioning ofthese individuals revealed use of antimenopausal hormone replacementtherapy through combined administration of estrogen and progesterone.Removal of data contributed from these individuals dramaticallydecreases variance in these test groups. The pharmaceutical companyinitiates a new study to examine the potential interactions of the testsubstance with estrogen, progesterone, or a combination of estrogen, andprogesterone, in normotensive, mildly hypertensive, and severelyhypertensive females in premenopausal and postmenopausal groups, furthersubdivided by history of hormone replacement therapy or exposure to oralcontraceptives.

The invention disclosed above is also applicable as both a system andmethod for monitoring and improving the design, performance, marketingand use of vascular stents. Stents are devices that are adapted to beimplanted into a patient's body lumen, such as a blood vessel, tomaintain the patency thereof. In particular, these devices are veryuseful in the treatment of atherosclerotic stenosis in blood vessels.Stents are generally tubular-shaped devices which function to hold opena segment of a blood vessel or other anatomical lumen. They areparticularly suitable for supporting and holding back a dissectedarterial lining which can occlude the fluid passageway therethrough.

Stent properties can be broadly characterized in two ways. Stents can becategorized according to their physical properties. Such physicalproperties include, as described above, the ability of certain stents tohold open or further open a narrowed stenotic segment of a blood vessel.

Alternatively, stents can be classified according to their chemicalproperties. Such stents may be used as physical repositories forchemicals (e.g., special coatings or drugs), wherein the chemicals maybe impregnated in the physical material of the stent such that they arereleased at an appropriate time or rate to achieve certain medicaleffects within the vascular system. Such chemicals may have globaland/or local effects within the vascular system. For example, a stentcould be deployed at a site of vasculopathy to provide a localtransudation of chemical to diseased endothelium. Simultaneous with itsuse as a chemical repository, a stent may also gradually andcontinuously exert pressure radially (i.e., outward) from within thelumen of a vessel segment, thus achieving the same result achieved byforced balloon angioplasty. Consequently, the results may include agradual reduction of stenosis and/or the resorption/remodeling of plaqueby, among other mechanisms, either the dissolution and absorbtion ofcalcium contained within plaque or through the break down of cholesterolesters that may be present.

Among the types of chemicals that can be used with and/or delivered viastents are: (a) agents that reduce platelet aggregation (e.g., Aspirinor Plavix); (b) agents that reduce local inflammation (e.g., Persantine,statins, or Cox 2 inhibitors); (c) agents that reduce local calciumaccumulations (e.g., chelators like EDTA); (d) agents that reduce localcholesterol depositions (e.g., statins or certain enzymes, like acholesterol esterase, that actually will elude cholesterol from the siteof the vascular lesion); (e) agents that cause local vasodilation andreduce the spasm-induced by placement of a statin (e.g., Paclitaxel,Sirolimus, Persantine, statins, Papaverine, nitric oxide, or NitricOxide synthetase-ENOS or INOS).

A stent may be made of material that is capable of being completelyreabsorbed (much like an absorbable suture (i.e., once the medicinaland/or mechanical effects are complete, the stent material graduallydissolves). In the unlikely event a dissolving stent fragments, any suchfragment would also readily be dissolved and reabsorbed.

The use of Dynamic Vascular Analysis (DVA) (formerly described as DCA orDynamic Cerebrovascular Analysis) methodology described above has beenuniquely applied for the monitoring and improvement of the design,performance, marketing and use of vascular stents. DVA is particularlyapplicable to evaluating stents because it enables the real timemonitoring of the dynamic components of blood flow (within a singlepulse or multiple pulses) to ascertain the physical properties andperformance of the vasculature prior to, and in response to, stentplacement. These measurements can be made in areas of the vasculaturethat are both proximate and distal to the location of a stent.Importantly, DVA-assisted stenting considers the global effects of stentimplantation, which is a distinct improvement over traditional stentingand stroke risk monitoring methodologies that only considered adiscreet, cross sectional view of the flow effects at the point of (orin close proximity to) a carotid blockage. DVA-assisted stentingmeasures all of the areas of the intracranial vasculature, as well asthe arteries supplying those areas, to determine the flow effectsbefore, during and after a stenting procedure. DVA further enables newuses and optimized placement of stents (including monitoring extraneousevents associated with stent placement such as emboli occurrence, etc.),new indications for existing stents, new designs for future stents(including new ways of marketing/specializing stents), among otherthings.

As described above, DVA involves the analysis of the TranscranialDoppler data (TCD). As applied to stenting, DVA can include TCD and/orIntravascular Ultrasound data (collectively “ultrasound data”) that iscollected and evaluated (via software) as a function of time andvelocity. Among the factors that can be measured and considered whenevaluating stenting efficacy and procedures are (a) a simultaneousconsideration of the ultrasound data values (peak systolic velocity(PSV), end diastolic velocity (EDV), peak systolic time (PST), enddiastolic time (EDT), mean flow velocity (MFV), systolic acceleration(SA), pulsatility index (PI), the natural logarithm of the SA (LnSA))for each of the established 19 vessel segments within the cerebralvasculature; (b) a comparison of the ultrasound data values against areference database to quantify the degree of variance from mean values;and (c) a series of indices (blood flow velocity ratios) derived fromthe ultrasound data values that are representative of the vascularstatus/performance/health of each the 19 vessel segments.

The derived indices include:

-   -   1. Dynamic Work Index (DWI or Acceleration/Mean Flow Velocity        Index (VAI))=(the natural logarithm of the Systolic Acceleration        value divided by the Mean Flow Velocity value and/or reciprocals        thereof). Thus, the DWI relates to the force of flow to the mean        flow velocity and describes kinetic efficiency of a segment in        moving blood forward.    -   2. Dynamic Flow Index (DFI or Velocity/Impedance Index        (VPI))=(Mean Flow Velocity value divided by the Pulsatility        Index value and/or reciprocals thereof). Thus, the DFI relates        the mean flow velocity to the impedance (pulsatility index) and        describes how capacitance volume affects flow through the        conductance vessel; and    -   3. Dynamic Pressure Index (DPI or Acceleration/Impedance Index        (API))=(the natural logarithm of the Systolic Acceleration value        divided by the Pulsatility Index value and/or reciprocals        thereof). Thus, the DPI relates the force of flow to impedance        and describes the effect of capacitance vessel volume on the        force of flow.

The 19 intracranial vessel segments considered are depicted in FIGS. 33and 34. The vessel segments depicted in FIGS. 33 and 34 represent theleft and right vertebral artery (VA), basilar artery (BA), posteriorcerebral artery/PCA t (towards) (P1), posterior cerebral artery/PCA a(away) (P2), internal carotid artery/ICA t (towards) (C1), middlecerebral artery (Ml), anterior cerebral artery (A1), anteriorcommunicating artery (ACOM), carotid siphon (towards) (C4), carotidsiphon (away) (C2), and the ophthalmic artery (OA).

I. Stent Placement

In accordance with an embodiment of the invention, DVA may be usedidentify and localize the need, placement and efficacy of a stent afterit is placed. In addition to being used to determine the need for astent, DVA can be used to monitor and analyze downstream vesselperformance in evaluating the effectiveness of the stent and/or whetheradditional or other types of stents are required. This process differsfrom traditional stenting procedures in that traditional procedures onlytreat individual points of stenosis thereby potentially missing moreappropriate upstream vessel segments having downstream stenotic effects,but that are themselves not yet fully stenotic (i.e., the stent could orshould more appropriately be used on an upstream vessel segment that'sbecoming imminently stenotic). Under such circumstances it is alsoimportant to be able to use drug-impregnated stents at an upstream pointbecause the pathogenesis at the downstream point of stenosis may not besufficiently advanced and therefore could be reversed with the use of amedicinally impregnated stent. Furthermore, optimized stent placementhelps minimize the need for (and indeed the damage caused by)angioplasty as a first alternative for clearing vessel blockages.Accordingly, use of DVA-assisted stenting procedures as described hereincan expand the number of approved stent indications.

Since DVA provides a highly sensitive means for thoroughly assessing thehemodynamics of the cerebral vascular system, it can particularlyidentify lesion types in the cerebral vascular system with betterspecificity than traditional angiography. As such, DVA enables andfacilitates the use of stents intended to effect coronary circulationinto the cerebrovascular system by way of the carotid artery andassociated vessels as well as into other vascular systems of otherorgans. For example, DVA facilitates the use of stents to treatnon-surgically accessible internal carotid artery lesions that are atthe base of the jaw or at an entrance into the skull. Similarly,DVA-assisted stent placement can be used in areas with lesions causingsignificant diminution of flow to the brain stem (e.g., lesions withinthe basal artery).

Indeed, as described in FIGS. 35A and 35B, DVA-assisted stentingprocedures are useful for evaluating the global effects of a stentingprocedure. In FIG. 35, it can be observed that both a localized andglobal increase in flow can be observed after a revascularizationprocedure (i.e., after stenting or angioplasty). Thus, DVA-assistedstenting procedures enable a treating physician to dynamically observeboth the localized and system-wide effects of a stenting procedure.Importantly, a global perspective also enables the treating physician totreat and manage the global flow increase that will likely be associatedwith stent implantation.

In accordance with another embodiment of the invention, DVA is used tomonitor the effects of emboli (which can then cause infarction)associated with stent placement. Since stent placement (and angioplasty)inherently result in tissue damage and emboli formation, the incidenceof emboli associated with such procedures must be monitored, and ifpossible, minimized. Accordingly, DVA can be used to identify apotential lesion before a full stenosis has occurred allowing a stent tobe placed therapeutically and without angioplasty. Similarly, DVAenables the treating physician to estimate the likelihood of embolioccurrence associated with stent placement at a particular locationbefore undertaking an invasive procedure. Thus, DVA-assisted stentplacement allows a treating physician to balance the benefits of stentplacement at a particular location against the risks due to emboliformation associated with that specific location.

In particular, it has been observed that the DVA measured Dynamic WorkIndex (DWI) is predictive of the microcirculatory effect of stentplacement at a particular vessel site. As depicted in FIG. 36, a plot ofDWI versus DFI can predict the likely effects of carotid stenting (andthus allows a treating physician to balance the potential risks andbenefits from stenting procedure prior to surgical intervention). Inparticular, it was observed that there is little benefit to be gainedfrom performing a stenting procedure on patients with DWI values aboveapproximately 0.16 due to excessive perfusion and the potential effectsof emboli formation. Similarly, it appears that patients with DWI valuesbelow approximately 0.10 have little need for a stenting procure (i.e.,there is minimal if any flow impedance). Finally, the data reveals thatpatients with DWI values between approximately 0.10 and 0.16 obtainmaximum benefits from stenting procedures when offset against thepotential effects of emboli.

In accordance with another embodiment of the invention, DVA-assistedstenting procedures are used to manage the incidence of inducedhyperemia occurring after a stenting procedure by enabling staged (orstepped) stent expansion. Pathological hyperemia refers to thebreakthrough increase in flow following any revascularization (i.e.,stenting) procedure. Downstream vessels are particularly susceptible tosuch effects because they may have become weakened or atrophied (e.g.,decreased elasticity) due to minimal performance demands during the timeperiod (which may cover many years) in which flow has been diminished.

Staged (or stepped) DVA-assisted stenting procedures allow the treatingphysician to gradually expand the stent diameter after it has beenplaced inside the target vessel. In addition to minimizing the traumaassociated with the initial implantation (i.e., emboli occurrence),Staged stenting permits the treating physician to regulate the increasein blood flow as the stent is expanded. Since DVA is a dynamic processthat produces real time results, it can readily be used tosimultaneously monitor the reaction of down stream vessels in responseto gradually expanding stent (and thus minimize any risks associatedwith the increasing flow).

In accordance with another embodiment of the invention, DVA-assistedstenting can be used to enable and/or assist thin wire intravascularultrasound (IVUS) procedures. For example, a thin wire IVUS device canbe pulled across a stented vascular region whereby it passes through thepre-stent, stented and post-stent areas. As depicted in FIG. 37, whendata is evaluated following such a procedure, three distinct vectorsrepresenting the net effect on flow can be observed. This type of datais particularly important as part of, among other things, bifurcationprocedures and studies. Bifurcation procedures and studies entailstenting a blocked vessel and monitoring a second ancillary vessel thatshares a common blood supply and determining whether the increase inflow in the blocked vessel (due to stent implantation) impacts flow inthe non-blocked vessel.

II. Stent Design, Marketing and Selection

DVA may also be used to enable new ways of using, marketing and sellingstents to the medical community. Specifically, DVA-assisted stentingassists the marketing and design of new stents and helps optimize stentselection based on a patient's condition. DVA can also be used toevaluate and validate new indications for existing or newly designedstents, including for conducting clinical stent trials.

In accordance with another embodiment of the invention, DVA-assistedstenting can be used to enhance the pulsatile movement of blood instenotic regions and/or selectivity tailor stent design and selectionbased on individual patient needs. In particular, DVA-assisted stentingpermits a treating physician to tailor (or otherwise) optimize stentselection with regard to a wide number of patient variables, including,among other things, the propensity for re-stenosis, the presence oftandem lesions, the vulnerability to the effects of emboli, the locationof the lesion (e.g., at or near a bifurcation) and the overallrisk-benefit ration associated with the stenting procedure. Currently,it is not possible to foresee, prior to stent implantation, how astenting a particular vessel affects the dynamic components of pulsatileblood flow. For example, it is not known what a stent does to thepulsatile and laminar components of blood flow.

It is generally presumed that angioplasty substantially damages anyremaining smooth muscle at the point of stenosis. As such, afterangioplasty procedures, there is no smooth muscle in the immediatestenotic area available to contribute to the perpetuation of thepulsatile wave. Thus, it is highly advantageous to design a stent thatcan mimic smooth muscle within the immediate stenotic areas (i.e., astent that can perpetuate the pulsatile wave better and preserve thecontribution to the pulsatile wave made by the smooth muscle adjacent tothe stenotic area). Thus, DVA-assisted stenting protocols can aide inthe design and development of stents with durable elastic propertiesthat better match the vessel wall tension at the point of placement. Inturn, such stents would also have improved drug delivery characteristics(in fact, the drug elution profile of such stents can be evaluated byDVA as a function of vascular performance at points downstream from thestent).

DVA-assisted stenting also enables custom tailoring of stents to meetindividual patient needs. For example, a stent can be tailored for aparticular patient containing that contains a unique chemical(s) toaddress a particular condition (e.g., a particular type ofarteriosclerotic plaque) and that has been individually sized for aspecific vessel segment and in view of that vessel's condition andpliability. Thereafter, DVA can be used to assess the performance of thestent after implantation and to determine whether a different chemicalagents vis a vis different types of plaque should administered. Indeed,it is envisioned that such stents could be designed to include, forexample, crystalline materials capable of generating a Doppler signalsuch that the stent could be detected and interrogated by DVA (andthereby be self-reporting).

In accordance with another embodiment of the invention, DVA-assistedstenting can facilitate formal FDA approval for the use of coronarystents in non-coronary vascular beds. Generally, the stents used in thecoronary vascular system can gain relatively quick FDA approval. Despitethis approval, many approved coronary vascular system stents have beenused by angiographers, cardiologists, and invasive radiologists for“off-label” treatment of, among other things, cerebrovascular lesions ina variety of vessel beds and vascular systems. In fact, such “off-label”uses of coronary vascular system stents in other vessel beds arebecoming more frequent for the treatment of cerebrovascular disease.

Given the increasing frequency of “off label” use of coronary stents forthe treatment of cerebrovascular conditions (as well as other blood flowconditions), DVA-assisted stenting provides a reliable means formeasuring the efficacy of such regimens. Thus, DVA-assisted stentingprovides a means for designing, marketing and establishing the utilityof coronary (as well as newly designed non-coronary) stents to be usedin a variety of organ beds including, among others, the cerebrovascularcirculatory system, the carotid artery cerebrovascular bed, theperipheral vascular beds, and even the gastro-intestinal vascular beds.Indeed, DVA can be used to support clinical trials by identifyinglesions that would be amendable to the placement of coronary stents innon-coronary vascular beds. Accordingly, DVA-assisted stenting mayfacilitate obtaining formal FDA approval for the use of coronary ornewly designed stents in non-coronary vascular beds.

1. A method of assisting a stenting procedure in a human or an animal,comprising the steps of: obtaining a first set of blood flow data;generating at least two blood flow factor values from said first set ofblood flow data; correlating said at least two blood flow factor values;and assessing blood flow based upon said correlated blood flow factorvalues.
 2. The method of claim 1, further comprising the step ofinserting a stent at a location within a lumen, the location based uponthe assessed blood flow.
 3. The method of claim 2, wherein said stent isexpanded in stages.
 4. The method of claim 1, wherein said steps ofobtaining a first set of blood flow data, generating at least two bloodflow factor values from said first set of blood flow data, correlatingsaid at least two blood flow factor values and assessing blood flow atleast on said correlated blood flow factor values occur before insertinga stent.
 5. The method of claim 1, wherein said steps of obtaining afirst set of blood flow data, generating at least two blood flow factorvalues from said first set of blood flow data, correlating said at leasttwo blood flow factor values and assessing blood flow at least on saidcorrelated blood flow factor values occur after inserting a stent. 6.The method of claim 1, wherein said at least two blood flow factorvalues include at least one of a mean flow velocity value, a systolicacceleration value, a pulsatility index value, a natural logarithm ofsystolic acceleration value, a peak systolic velocity value, an enddiastolic velocity value, a peak systolic time value, an end diastolictime value, an acceleration/mean flow velocity index value, avelocity/impedance index value and an acceleration/impedance indexvalue.
 7. The method of claim 1, further comprising the step ofcorrelating at least three blood flow factor values.
 8. The method ofclaim 1, wherein said step of obtaining intracranial blood flow datacomprises use of emissive and reflective wave technology.
 9. The methodof claim 8, wherein said emissive and reflective wave technologyincludes ultrasound technology.
 10. The method of claim 9, wherein saidultrasound technology includes Doppler technology.
 11. The method ofclaim 9, wherein said ultrasound technology includes thin wireintravascular ultrasound technology
 12. The method of claim 8, whereinsaid emissive and reflective wave technology includes laser technology.13. The method of claim 1, further comprising the step of generating areference data set of correlated blood flow factor values.
 14. Themethod of claim 1, further comprising the step of supplementing areference data set of correlated blood flow factor values withadditional correlated blood flow factor values and data.
 15. The methodof claim 1, further comprising the step of comparing said correlatedblood flow factor values with a reference data set of correlated bloodflow factor values.
 16. The method of claim 1, further comprising thestep of designing a stent.
 17. The method of claim 16, furthercomprising the step of infusing a stent with at least one chemicalcomposition.
 18. The method of claim 16, further comprising the step ofcoating a stent with at least one chemical composition.
 19. The methodof claim 16, further comprising the step of inserting the blood flowfactor values into a schema.